A response to an NPC in-game if you don't have the DLC is <Buy Premium Content Now>
Also you can check what Premium content you have in your Journal.

EA? I'd love to see System Shock and Dungeon Keeper on GOG.

That's just...dirty. Haha. I hope I don't run into them. :(

Not only that, as soon as you have talked to an NPC who offers a premium content quest that quest is added to your journal, and the only way to remove the entry is to buy the DLC and finish it. :o

Let it be Atari. (Or Sierra. Or LucasArts.)
Let there be Planescape. (Or Phantasmagoria. Or Grim Fandango.)
Then my PC collection can live on happily forever. (And ever.)
*crosses fingers* (*toe fingers too*)

I think that the next big one is Atari (see The Witcher, Planescape re-release).
And then the next, Eidos (but there is Square to agree with it). I think we will never see Blizzard here, since they got their own store and there is SC2 and expansions coming out, and putting up Battle.net too. I doubt they'll release older games in the next 1,2 years, only if they try a different approach with their new system.
LucasArts, I highly doubt that it will be in GOG before mid-2010, if they ever do, and after releasing in other DD services too. They still have to release other games on Steam, the little ones like X-Wing series, Maniac Mansion, Grim Fandango...and maybe a X-Wing remake.
I hope SS1 and SS2 will be released close to the Thief series here on GOG. (I know, not an easy thing...) =D

D2D have just dropped a whole load of their classic Lucasarts stuff by 50%. Possibly getting as many sales as possible before they appear on GOG?

Sir all I have is my dreams and I thank you not to spoil them :p

Hmm thanks for the tip, although I've never used D2D.

Sierra is Activision now. So I'm not entirely sure I'd be keen to see them here.

King's Quest I EGA - Only $9.99. Buy now and get a free "I'M A SUCKER" t-shirt!

Really? Didn't know that...

And the newer games will be like $9.99 per level/mission/racing track/whatever?

If planescape does happen to show up and assuming my head doesn't explode from excitement, I'll be buying it for at least 2 people other than me. Especially if it comes with the soundtrack
Its not as bad as you think, he's a guy who stands off in a corner of your camp and never once initiates contact with you. He doesn't stand there like a spruiker shouting about the bargains to be had on the marketplace and if you don.t have it, you can tell him to sod off (which should also close the quest so it doesn't mess up your nice clean journal)