Simon,
FWIW, 5.0.2 also took my 2011 MacPro down.
Here are my details after installing OS X 10.8.3 (today):
Model Identifier: MacPro5,1
Kernel Version: Darwin 12.3.0
Here is my graphics config in case it's needed:
Chipset Model: ATI Radeon HD 5770
Type: GPU
Bus: PCIe
Slot: Slot-1
PCIe Lane Width: x16
VRAM (Total): 1024 MB
Vendor: ATI (0x1002)
Device ID: 0x68b8
Revision ID: 0x0000
ROM Revision: 113-C0160C-155
EFI Driver Version: 01.00.436
I will try with 3D acceleration enabled once I have backed up my VMs.
Rob