From what I can tell I have vSGA working in a test server with ESXI 5.0. I get full Aero in Windows 7 and a WIE score of 3.0 for graphics (2.7 in Windows 8 where the vSGA driver is not used, a generic microsoft driver is used instead). I can run a few 3D (DirectX not OpenGL) apps from the VMware console but the biggest advantage is that Windows 8 uses the GPU to help remote desktop so with Windows 8 and vSGA there is almost no need for VMWare View or Microsoft RemoteFX.
I beleive only NVidia GPU's work, it certainly did not work for me when I tried an ATI GPU (HD5770) but you must have them installed durung the ESXI install, I had a 460GTX installed and have now downgraded to a 450GTS for power reasons. I have read about the VIB and as far as I am aware its installed automatically at install if the hardware is there. I can confirm VM's with a vSGA addapter and DXDiag reporting acceleration although I know there is not a lot of info around on the net so I think its implementation is still not up to a full release standard.
All that said a windows 8 VM with a passed through ATI card is better still, full GPU power to the remote desktop acceleration. I can run Unigine Heaven benchmark over RDP at 30+ FPS.
Regarding passthru DXVA I can only get hardware acceleration to work when using ATI's own codecs and I cant confirm that is DXVA, with FFDShow, DivX and LAV specifically using DXVA it fails with green screens or no video. I have only tried a 5xxx and 6xxx cards though. Its not always possible to select ATI's codecs and even ATI screwed up when they released a new driver version which disabled them so I am stuck with version 11.4 for the moment to keep using good codecs. Annoyingly DXVA does work with vSGA!