After dealing with countless crashes, and stuttering, I got fed up, and reinstalled my drivers (latest nvidia 260.89) - every time you do this, it disables SLI.

I decided to launch the game with a single GPU, and its been stable, smooth, and stutter free since.

If you are running SLI (in my case, dual GTX 285s) I recommend you try this out until they identify the problem and fix it.