Tested and working on W7, including 64bit version!
Doomer's tests:
- 1nsane
- Beneath a Steel Sky
- Beyond Good and Evil
- Duke Nukem 3D
- Duke Nukem Manhattan Project
- Earthworm Jim 1 & 2
- Earthworm Jim 3D
- Kingpin - Life of Crime
- Lure of the Temptress
- MDK
- MDK 2
- Megarace 1 + 2
- Megarace 3
- Postal
- Postal 2 + exp
- Prince of Persia Sands of Time
- Screamer
- Teenagent
TheCheese33's tests:
- Freespace 2
Miaghstir's tests:
- Arx Fatalis
- Ground Control
- Ground Control 2
Kavazov's tests:
- FlatOut
- Neighbours from Hell: Compilation
Miaghstir's tests:
- Abe's Oddysee
- Broken Sword - The Sleeping Dragon
- Broken Sword II - The Smoking Mirror
- Earth 2150 Trilogy
- Fallout
- Fallout 2
- Fallout Tactics
- FlatOut
- Giants - Citizen Kabuto
- Hostile Waters - Antaeus Rising
- Pro Pinball - Big Race USA
- Sacrifice
- Simon the Sorcerer
- Tex Murphy 1 and 2
- The Feeble Files
Namur's tests:
- Heroes of Might and Magic 3
- Settlers 2 Gold
- The Guild Gold
gbarules2999's tests:
- Unreal Tournament
- Unreal Tournament 2004
bastont's tests:
- Gorky 17
Found a game that don't work on W7 (yet?=)
- Messiah

Freespace 2

It shouldn't be a surprise that Rey Ozzie is trying to keep Windows 7 from falling into XP and Vista's trap of not having programs install right for a year. I'm excited.

I'm happy too cause some titles like "Atari 80 classic games" does not run on Vista, but it works fine on 7! =)

Does this mean there are new installers that correctly add them to Games Explorer, or only that the games themselves work?
Seeing how I own all of 'em except MDK, I'll be redownloading them ASAP if they do, in fact register themselves in GE, otherwise I won't have to bother yet.
Arx Fatalis works - and is added through Windows' own Legacy Games detection
Earth 2150, FlatOut, Ground Control, Oddworld: Abe's Oddysee and Sacrifice do the same for me
Ground Control: Dark Conspiracy do NOT register itself, but DOES contain the necessary DLL file (when using it to register manually, I have 2 icons, one to start the regular game, and another to start the expansion - the first "legacy" detected by windows, the other registered as a "games for windows" game).
Ground Control 2 is correctly added to the Game Explorer by its installer (and also detected by the legacy games thingie - so there's 2 icons pointing to the same thing).
I'm pretty sure all the other games work as well (I haven't installed all my games in W7 yet), but wether or not they're added nicely to the Game Explorer is another matter.

I don't think the Games Explorer issue has been resolved yet (after all, GOG isn't officially compatible with 7 yet) but that's a minor thing; the games themselves work perfectly. Microsoft's intention was that virtually everything that worked with Vista will work with 7, and this has certainly been the case for GOG games.

Oh yeah, there's a game explorer in Vista ...

Well isn't windows 7 basically just the finished & optimised version of vista? You'd expect pretty much anything that works in V to work in 7

When I used 7 I got the strange feeling I was on a hybrid XP/Vista system. I loved using it, it was 100% stable for me and performance was a dream. I eventually had to format tho and went back to Vista x64 and have been using it since (Vista x64 seems to run better than x86 vista for me.) .
Already planning on getting Windows 7 Ultimate this October, but its good to see the compatibility is keeping up.

I purchased more some games on GoG.com and its working!
* added on 1st post

You should edit your first post, so that people can see it as a sort of a list.
Also add these two, they work perfectly.
FlatOut
Neighbours from Hell: Compilation
The only problem is the Games Explorer issue, but I think the GOG team can fix that easily after they announce support for 7.

ops, sorry, 1st post edited =)
* I placed all feedbacks on my post =)
I'm not considering if Games Explorer works or not, this "tool" is a bit bugged, I have +- 400 titles installed on my home computer and some games just crash it, iincapacitating me to open it again, when I try to open it just appears and disappears in seconds =(
* this failure occours on Vista too

Tex Murphy 1+2 (Mean Streets and Martian Memorandum, respectively) work fine, and the installer registers both games nicely in Games Explorer.
And about "fixing that after they announce support for Windows 7", they already are fixing it, one game at a time (though what they're going to do about the games that both get registered AND added through Windows' legacy game detection, if anything, is another matter).
Actually, I can't say I've played a game that DIDN'T work from here (missing icons in game explorer notwithstanding), and I have the following installed (full list, some games have already been mentioned, ignore those and add the rest):
1NSANE
Abe's Oddysee
Arx Fatalis
Beneath a Steel Sky
Beyond Good and Evil
Broken Sword - The Sleeping Dragon
Broken Sword II - The Smoking Mirror
Duke Nukem - Manhattan Project
Duke Nukem 3D
Earth 2150 Trilogy
Fallout
Fallout 2
Fallout Tactics
FlatOut
Giants - Citizen Kabuto
Ground Control and Expansion
Ground Control II
Hostile Waters - Antaeus Rising
Kingpin - Life of Crime
Lure of the Temptress
MDK2
Prince of Persia The Sands of Time
Pro Pinball - Big Race USA
Sacrifice
Screamer
Simon the Sorcerer
Teenagent
Tex Murphy 1 and 2
The Feeble Files

Beyong Good & Evil
The Guild Gold
Settlers 2 Gold
POP Sands of Time
HOMM3 Complete.
Have these installed and they're working fine on Win7 64 bit.

I tested both Unreal Tournaments and played without a hitch.