It's the same in the US (but in dollars), not just EU. I don't really understand what PopCap is doing.

Why should it be different for media?
Because digital distribution isn't based on a geographical region. It is not tied to the same distribution channels that physical media is, there are no importing costs, no delivery costs (besides that for bandwidth, which is the same worldwide); it's being served to people worldwide from the exact same source so any change in pricing beyond that of a direct currency exchange and the addition of applicable taxes is purely artificial.
Different currencies have varying relative values
Now in the case of the US/Japan, our curriencies carry almost the exact same worth (100 yen is always basically 1 dollar give or take an average of 10 yen either way) -- due to the yen being tied to the dollar during the post World War period when the US was basically in control of Japan.
If we actually look at games, movies, whatever, they all carry the exact same production cost for the actual item -- it was after all, only made once, in one country. Any additional costs then, are going to be on local production, packaging, localisation and other distribution related costs. And none of those costs should ever justify a 100% markup on the price, especially when it's possible to simply import the same item from another country for far less. So if your local distribution channel is making a product that much more expensive, there is a problem within that channel which is costing you profit; profit you then try to get back by fleecing the customer instead of fixing the problem.
So how do those local costs truly affect digital distribution? And let's not simply fall back on the "local retailers demanding digital distribution be more expensive" line, that's just an indication that they are a part of the above problem and should themselves concentrate on solving that problem, reducing their pricing, and actually for once, trying to make their service desirable without demanding these artifical price hikes that really do little to help their overall profits and just deter would be customers from parting with their money in the first place!
It's the same in the US (but in dollars), not just EU. I don't really understand what PopCap is doing.
This is standard for Popcap and other casual gaming portals. They all have an RRP of $20. Some of the portals, such as Bigfish offer "membership" options in which, by agreeing to buy x number of games in y space of time, you can get z amount off. The maximum being 65% off if you agree to purchase a minimum of 12 games (at that price) in a 12 month period -- bringing the actual price of games down to $6.99. People who don't want to join, will pay $19.99. Spintop also offer reductions, but it's along the buy x number of games at once and get y amount off of your total purchase (it's not a great deal really).
But looking at the Popcap site, they don't appear to do any such discounting. The reason for the 50% price difference (in most cases) on Steam, is almost certainly down to their sales figures that Steam provides them. It has most likely shown them that they sell significantly more (and thus, make an higher overal profit) then when their games were priced at $19.99.
The primary audience who are likely to purchase direct from Popcap, are also most likely to not even know that Steam exists, and thus, would have no idea that they could get the game cheaper (and without DRM which they probably don't even give a damn about).

Well, the price point should be cheaper in general for digital distribution. If it isn't then something is not right. Something is clearly not right at the moment since I can get Fallout 3 for example cheaper at a retail store than via Steam.
The reason, however, is not merely regional pricing on Steam, because Steam does not price in NOK, only Euros. The reason is the unfortunate combination of the Euro currently being very strong compared to NOK, as well as the VAT not being applicable to Norway specifically since we have no VAT on digital media by law.
Hence, I would actually welcome an even more regional pricepoint on Steam, in our currency, as stuff would probably become cheaper that way. Economy behaves in strange ways...

Thread, I summon thee. RISE!
I just bought PVZ through Steam, because it is on sale this week. Wow. The demo didn't really catch my attention, but since it's on sale, and my 2 younger bros are bugging me to buy it, I thought why the heck not. And now, I'm hooked on to it. It's been a while since I got hooked on to games, but PVZ rezzed the gamer within again. Considering it's made by a casual-games company, I'm surprised how addictive (and charming) this is. Definitely money well spent
Also, for those of you hesitant to buy it because it's touted as a Tower Defense game, rest assured, you have nothing to worry about. I too dislike Tower Defense games, often seeing them as a waste of money. However, it's a very different league of Tower Defense game, to put it loosely. It's more action than strategy during some stages, and of course there is a good variety of minigames and puzzles to keep you occupied. Plus, there are altogether about 50 plants or so, each with its own attributes. The game just doesn't get stale in any way, because of new challenges for every stage/level.
JUST.BUY.IT. Especially since it's still on sale.

I bought it for my Mum. She loves it. So do I.
And yes, tower defense has never really done it for me, but this game boils it down to perfection (is that a saying?)

I bought it too. Not finished it yet but well into the fourth day, and yes, enjoying it. Bought it together with Defense Grid: The Awakening which I'd heard was another stylized tower defense. I love tower defense.
PvZ isn't tower defense at all though, since the enemies just come hurtling at you in fixed lanes across the screen and there's no path for them to follow. Ultimately it all boils down to managing your sun well, which is easy if you pop down 5 sunflowers / sunshrooms right at the go. Hold off the first couple of zombie with walnuts and/or bombs until you can afford repeaters, then it's pretty much smooth sailing from there on in any level. Some of the night levels are more strenuous though as you have lower-damage plants in general but can place a lot more of them.
Defense Grid is more of a standard tower defense game, in that you have a path and places along it in which to place towers, which you can then upgrade. But it's done in stunning 3D, and the paths are often nonlinear. You also need to take the third dimension and line of sight into account which adds a bit to the strategic mix. There's a lack of missions though, even if every one of them is uniquely rendered and boasts fairly lengthy gameplay, several modes to promote replaying, and some twists and turns.
I plan to get Trine next. Really had a revitalization of buying stuff on Steam, although I'm sticking to the Indie games for the time being, there's some real Indie gems I've missed during my one-year long boicot of Steam.

Trine is actually very good when the devs aren't breaking it with patches =P (They actually have since fixed it again, so you have little to worry about). It maybe $30 but it's certainly got a lot of playability in it.
I bought it for my Mum. She loves it. So do I.
Yup, PvZ is a very good family game as it were, I think at least 3 or 4 members of my family also have their own copy now too. I'm hoping we'll eventually see a sequel to it.

I Just got this game recently as well, its definatly addictive but my only complaint is its way to easy. I'm on stage 4-7 or something and I haven't yet even considered that I might lose. Infact on quite a few of the stages by the final wave I have enough firepower to cut them all down before they can even get onto the screen properly.

Yes, it's definitely way on the easy side. I guess it's supposed to be a family title ... but I'd appreciate difficulty levels, or at least being able to turn off the default grampa mode.

Stop making me feel old, I got stuck at several points

I had the same issue as Ralackk, the game was far too easy.
I need at least some challenge, but the one here was just too low, I could not get into it, even if it did have charm and fighting with plants and zombies (& fungi) :|

Yeah, the first time round is certainly very easy, but it does wrap around although I'm not sure if it really ramps up the difficulty for the main game. But some of the bonus level/mini games can be a little tricky.

The second go-around on the "campaign/adventure/whatever-they-call-it" can be a little wonky if only because Crazy Dave chooses three plants for you and if you don't have enough seed slots and he chooses some crappy plants for you, you may have a bit of a hard time. Other than that, I don't think it's necessarily that much harder on your second run through. But yes, the minigames and such can be a little rough. I just -barely- managed to get the 20 flags on Survival (endless) so I have the achievement. Right now, I'm just money farming with my zen garden and such to build up enough cash to grow my Tree of Wisdom enough so I can get that achievement.
It is a ridiculously fun and time consuming game. Excessively great value for the price.

I don't know about you guys, but I definitely sweat quite a bit on the night time, fog-filled pool levels. I'm at level 5 now, only lost about twice so far. Although I still end up winning on the first try most of the time, I appreciate the difficulty not being too high this time round, yet constantly challenging me with new enemies and plants.
I think PvZ definitely deserves the hype and praise it got, more so than the overrated (imo) World of Goo