Robert McLaws cleared up some misinformation at Windows Now surrounding recent leaks of Windows 7 (e.g. 6931, 6956), but what I found interesting was that Betanews reported on the semi-transparent glass borders on windows, claiming the possibility of WARP10 usage within a virtual machine...
Also, in a development that should evoke the comment, "Oh, yeah!" from everyone who thus far has seen it but not noticed it...the Aero windows have semi-transparent borders. Of course, that's a feature that premiered in Windows Vista. But in a virtual machine, semi-transparency doesn't typically work because the virtual video driver in Microsoft's Virtual PC does not enable full DirectX 9 compatibility.
This could indicate either that the screenshots (if valid) were taken on a more sophisticated platform than normal (still possible), or that Build 6951 contains the new feature blogger Long Zheng revealed two weeks ago: a software rendering engine currently called WARP10 that enables graphics made for DirectX 10 to be rendered on cards that could just barely physically support DirectX 9.
I don’t think the author has ever seen Windows 7 running in a virtualized environment so I’ll help put this one to bed right now. Here’s what newer builds of Windows 7 look like in Hyper-V (ignore their incorrect build number). Do you see transparency?
Windows 7 Build 6956 freshly installed in Hyper-V environment