Here is my Version of the new Mac Pro (Early 2013): ;-)
System Details:
Asus Rampage Gene 2
i7 920 (2,67GHz) @ 2,93 GHz
6 GB RAM
ATI Radeon 5850
1x Intel SSD 520 (120GB) for OS X (10.8.2)
2x WD Raptor (120GB) for Windows and Games
i'm running OSX 10.8 ML very well. Only my graphics card ATI Radeon 5850 is a little bit slow in 3D Gaming. When I play World of Warcraft on medium details@1920x1200px it is not flawless.
I've tested with the Bootloader Chameleon and Clover (same results) with Bootflags: <key>GraphicsEnabler</key> <string>Yes</string> <key>AtiConfig</key> <string>Uakari</string>
In "About my Mac" it is shown as a ATI Radeon HD 5800 Series and when I start CInebench or Luxmark it is shown as "ATI Radeon Cypress Pro Prototype". Cinebench Score: 30 / Luxmark: 625