Miaghstir: By the way, is OpenGL even allowed to be used (at least as a choice for the user) for games wanting the "games for windows" labelling? I've been under the impression that it wasn't.
Navagon: Put it this way: I can't think of one GFW game that features OpenGL support. But I doubt MS openly state to the public that they refuse games the GFW label on the grounds that they support the OpenGL.
As you point out, Direct X as a suite is fast becoming obsolete. Maybe MS plan a switch to OpenGL as the final stage of that process. It's not like open source or the advantages thereof are alien to them after all.
But all this is just speculation really.
Eh, nevermind... I researched myself, and [url=http://msdn.microsoft.com/en-us/library/bb173456(VS.85).aspx]found this[/url]:
1.7 Direct3D Support
Requirement
If the game uses Direct3D, then the minimum version supported must be Direct3D 9, and Direct3D must be the default. Overall, I think the GFW label is quite good, as it easily filters out older technologies that may not work on newer systems (16-bit apps and non-multicore-awareness, for example), and makes sure that the game will continue to work for quite a while (well, that has yet to be proven, seeing how Win7 is only the second version for which the label is used, but it seems that the requirements are quite future-proof).