I was doing a little digging on the GeForce 8800 GS graphics card in the latest iMac. The performance didn't match up with the GSs that I'd seen. Guess what? It's really the GeForce 8800
M GTS. Specs:
Pipelines 64 - unified
Core Speed 500 MHz
Memory Speed 800 MHz
Memory Bus Width 256 Bit
Memory Type GDDR3
Max.Memory 512 MB
Shared Memory No
DirectX DirectX 10, Shader 4.0
Power Consump 35 Watt
Transistors Million
The new card should run anything from COD4 to WoW without issues and can support up to 2560x1600 on an external monitor via Dual-Link DVI-D.
http://www.techpowerup.com/gpuz/43pxg/