I'd love a appdb<->gog collaboration, but I guess it'd be financially unfeasible right now. Thet vague "in the future" statement instills confidence though.
I just want to throw this out there for our wine-using friends:
Sometimes it happens that your desktop resolution gets fucked up when your wine app crashes, or if it doesn't "clean up after itself" properly.
Just switch to a terminal and type in xrandr -s 0 .
This will reset your deskop resolution to whatever it was, even if the GUI tools insist nothing's wrong. I had that happen to me time and time again when I used Ubuntu half a year ago, and it pissed me off to no end.

Er... one of the first things I tried, was to run MDK under Wine in 640x480 desktop emulation...
The install runs just fine, the only problem being the GOG.com installer window being partially beyond the lower right corner of the screen. (But it does the same on Windows anyway.)
Then, only the upper half of the game screen appears, and the whole thing is incredibly slow.
I'm currently getting Fallout from GOG.com, and when I'm done, I'll try that with Wine.
However, I'm starting to think that the emulated desktop could have taken a toll of its own as well, so I'm going full screen.

I would like to second the idea of having some kind of wine seal saying which games work well with wine. If we do the testing (by which I mean playing ;) ) then all GoG would have to do is modify their website a little to add some kind of a linux/wine seal to games that people have told them play fine. Either that or just link to Wine appdb for games that have an entry.
I would also like to see linux native anywhere that is possible, but understand that that isn't (and unfortunately) probably shouldn't, be GoG's priority right now.
Great idea over all though. I am looking forward to playing fallout which I missed the first time around.

Apart from support for Wine, I noticed that also DOSBox is used for playing the DOS games. Maybe GoG could make those games work with the *nix version of DOSBox, no need for Wine there.
Even better would be if those games are in there own Ubuntu repository.

The installer for Die By The Sword works fine for me in wine (ubuntu as well).
So does the game, I am happy I finally found ths nice violent game! :)

GoG might have more to gain than other distributors from catering to Linux users. There is some overlap in attitude (anti-DRM and anti-piracy), and older games are probably easier to make work in Wine/dosbox.
First step: make sure that whatever they do to the games doesn't cause extra trouble for Wine/dosbox. (I don't know if this is the case, since I'm downloading my first now.)

Though I can't find it now, I saw a post about Giants: Citizen Kabuto working on Wine.

Most older games written for Windows can be made to run under Wine, many of them near-perfectly. That's because the older versions of DirectX are well-supported by Wine now, whereas, say, DirectX 9 and 10 aren't (actually 9 is pretty well covered now, too). Games written for DOS, as others have pointed out, are handled by DOSBox.
Linux users will notice that many brand new games programmed by the big boys run fine under Wine and/or Cedega as well, whereas games released by lesser development houses often have problems. This pretty clearly has something to do with the coding practices and experience of the respective programmers. I've only been at this Linux thing a few months, but I've already got a good feel for what is likely to run well under Linux and what is not.
In any case, there's a site Linux users can go to to learn how to get their Windows games running (sorry if it's been mentioned already; I didn't read the whole thread): [url=http://appdb.winehq.org/http://appdb.winehq.org/[/b[/url]]
Just go there and type a game's name into the search box. You can find out whether anyone's gotten the game to run under Linux and all the details about how they did it.

according to the wine site, when you look at the files in the latest build, they haven't even started the DX10 files needed to run DX10

Linux only here...
every time i buy a game is a little gamble, but of 9 game tryed to this date 2 are about unplayable, and a third is barely so.
most of it is because the added launcher or what is the part of program that gog prepended to the game to make it play right on winxp, here a not tampered version of the game could be probably very playabre with wine or dosbox.
the other 6 games work well, eiter directly in dosbox, scummvm or with wine/cedega (well, one has a graphic resolution problem and another required a little install and configuration work but now play well)
definitly an alternative download containing not tampered, simple zip or original installer version could help a lot with many games (quicker for dosbox and scummvm use, or more useful support directly from the wine community)

Beware! Zombie thread, resurrected from the dead!