Like fangbite wrote in my other thread, I think it is good, if we could make a list, what game from GOG works good/ not so good with Ubuntu/Linux and Wine.
I will edit this post with alle tested games. :)
I take the start:
Games with Wine tested:
Descent 3
Fallout
No Problems with the installation, starting the game also worked without any problems.
Fallout 2
No Problems with the installation, starting the game also worked without any problems.
Freespace
Giants: CItizen Kabuto
Hostile Waters: Antaeus Rising
Kingpin
M.A.X.
M.A.X. 2
MDK 1
Original War
Perimeter
Sacrifice
Stonekeep

Gabriel Knight 3 works, but only in software rendering mode (it's ugly). It isn't rock stable either: occasionally crashes.
You need to set up a cd-rom drive in winecfg else the game shows a 'Please insert CD 1' error.
Wine-1.2-rc2

There are several reports on Wine's bugzilla page that Haegemonia is launching correctly under Wine-1.2-rc3 and is fully playable at last.

I think this post is a bit redundant when winehq.org already exists, but it is an obviously useful tool nevertheless. Still, I would love to see it become a feature of the site supported by the people from gog.com
Here is my contribution:
Ubuntu 10.04
Ati open source drivers (I own a 3870x2, :()
Wine 1.1.42
- Fallout: Perfect. It freezes form time to time, nothing important.
- Beyond Good and Evil: Don't read the memory of the system right. I think it runs though, but too slow.
- Oddworld: Abbe's Oddysee: Runs good, except maybe the cutscenes that seem to play a bit slow. Sadly, the sound tends go mute way too often, to the point of making me switch to Windows with great frustration (not that the game itself is a joyride either).

Arcanum works with wine 1.2, unofficial patch, and res patch to 1680x1050, but it's REALLY sssslllllooooowwwww..... (too slow for me to play as it takes a LONG time to move across maps...)
hopefully this is just a wine bug...
oops
Ubuntu 10.4
Catalyst 10.6 (4850 mobility 512MB GDDR3)
x86-64
P8600 4GB
[EDIT]
Sacred works as well... but I'm using the Steam version...
[/EDIT]

Greetings,
of the 30+ games I have bought off GOG so far, I managed to begin two.
Imperial Glory
Works great: Strategic map, land battles and naval battles work great. If there is a multiplayer mode I haven't tested that yet. You should disable Compiz though.
The only problem is: Sometimes the music stops after a land battle, but it kicks back in when you return to the main menu. But this could be specific to my system, since I have one of the infamous Creative X-FIs, which are known for causing trouble on any OS but Win XP (Vista drivers took over 2 years to appear at all).
Far Cry
I play this under Windows.
It works well with the DirectX as well as the OpenGL Renderer (though Crytek didn't implement every feature under OpenGL), the performance is good and there is no flickering or such.
The catch is again the Soundsystem. The quality is great but there is a distinct delay of about one second which is too much to be playable.
Maybe using OSS instead of ALSA could work and maybe "normal" soundcards don't show this behaviour.
Neither has problems being run on a Dualcore system (unlike some modern games like Monkey Island:Special Edition or Street Fighter IV ;) )
My System
Ubuntu 10.04 64bit
Geforce 7900 GTX with NVidia's proprietary drivers
Athlon 64 X2 4800+
-Burnout
Edit: Typos

Just tried realMYST with wine1.2 working but slow

Enclave works out-of-the-box in Wine-1.3.0. However, the speed issue/stuttering seems to affect Wine, too. Subtitles in the cutscenes are out-of-sync unless you disable cpu frequency scaling in Linux. The game runs in slow-motion for me unless I completely disable VSYNC both in the game and in the Nvidia control panel.

Two Worlds also works, after installing the Physx engine, native DX libraries and the Xact engine via winetricks. Playing the intros/in-game videos took me some time to discover, but finally I succeeded. There's a comment on the AppDB page of the game:
http://appdb.winehq.org/objectManager.php?sClass=version&iId=16889#Comment-61998
I haven't tried multiplayer yet.

Raptor: Call of the Shadows
There are two .exe files you can use to run the game. If you run rapwin.exe the game will work with no configuration needed. But if you run Raptor.exe wine will give you a descriptive error message telling you to install Mono for Windows. To do that you want to install winetricks.
wget http://www.kegel.com/wine/winetricks
sh winetricks mono26
Click through the installer and you're all set. The only thing different about Raptor.exe is it shows a launcher menu and you can set the resolution (2 options) and whether or not to use Fullscreen. rapwin.exe defaults to a window.

I have some good news, folks! Finally, Darkstar One works in Wine, at least with the latest development version: 1.3.0. It works out-of-the-box, no additional Wine configuration or native dlls needed. The only complaint so far: I cannot get in-game FSAA to work.

Hello,
Any info on Alone in the Dark and Phantasmagoria II? There are some platinum reports in APPDB.
Has anyone here tried yet?

Usually, dos games run smoothly via dosbox.
Would be interesting if GOG create an installer (. deb or. rpm) for dos games.

An addition to my comment on Two Worlds: multiplayer does not work in Wine: I can enter the game lobby, trading and chatting works but whenever I click on join a mission or quest nothing happens.

King's Bounty: The Legend works, but has some issues:
* performance is generally slower than on Windows (esp. when shadows are enabled)
* you'll need a native msvcrt.dll to avoid the frequent crashes when entering or leaving a battle.
* there's no animated mouse cursor in the game, only a plain white arrow.
* minor graphical glitches, e.g. water is not rendered correctly for me.
You'll need at least a native d3dx9_36.dll, or install the dx libraries by winetricks.
Despite those issues the game is playable and stable even after several hours of gameplay.
Fantasy Wars works almost out-of-the-box: only native dx libraries are required. Good performance even on the highest details. I'm not sure about the functionality of the shadowmap feature: I can't see any difference whether it is enabled or not. At least it doesn't cause graphical glitches like it does in Elven Legacy.
Wine-1.3.2
Nvidia 7600 GT