I just tried out 3D support on VMware Workstation 5.5.3 build-34685 running on Fedora Core 6 with WinXP Pro guest and ATI 9600 AGP card with the latest ATI proprietary drivers.
I ran dxdiag and clicked the Test Direct3D button. The spinning D3D cube came up jerked around for a few seconds and then dxdiag moved on to the next test (D3D8), after that the VMware Workstation crashed. I also noticed that the screen looks really crappy, you can see the scan lines which is very irritating.
I can send somebody the log if anyone cares to see it. You guys also might want to add "3D features only work with the nVidia/ATI proprietary Linux drivers" to your how-to page to help the brave but uninitiated.
I'll keep using Wine for now, but I've got my eye on you guys....