I'm having the same issue too.
It has happened 3 times in the last 3 weeks that I've had it.
Temperature at the times was normal, last crash tonight the CPU was at 54degreesC (the coolest it ever goes while in use).
I've got my normal set of applications open: iStat Menus, Adium, Firefox, X-Chat, Quicksilver, iTunes, NetNewsWire, Mail.app. None of these have caused issues in the past.
Model Name: MacBook Pro
Model Identifier: MacBookPro6,2
Processor Name: Intel Core i7
Processor Speed: 2.66 GHz
Memory: 4 GB
Extra Devices attached: Mini DisplayPort to DVI Adapter to my 22" screen
Keyboard and mouse are running via Synergy from another machine.
Also running optical audio out.
Here's a couple things I've noted when it crashes:
* All applications will freeze and the mouse can still move for about 5-10 seconds. Then the mouse will freeze too (it freezes as a pointer arrow, nothing beach balls).
* Most network connections are dropped. I lose my Synergy connection (mouse and keyboard) and iTunes (playing off a network drive) will stop too (it goes silent, not playing the same frame again and again).
* The most peculiar thing though, one time I was chatting to someone with Skype, and the video froze, the mouse froze yet I could still talk to the other person. This indicates that everything else is still running, the network is still able to keep up a stream and even the audio is still going alright.
Hopefully some of this information helps, I'll post if I work out something else.
Ducky