One thing I've noticed since day-one of Mac OS X, going back ten years now is that any time the ''international screen of death'' appears and freezes up and forces a restart, 99.9-percent of the time it is network related.
This flies in the face of the whole NVIDIA theory. It also doesn't seem to apply because there appears not to be an ''international screen of death'' in Lion.
I have also been experiencing this random freeze/crash/reboot issue, and because I have the ''automatically reboot'' on freeze option checked in preferences, I am not there for every crash, but it is indeed happing often because I hear the tell-tale ''bong.''
Whatever issue it is, most likely it will be fixed in the point-one update. This random freeze/reboot syndrome and the sudden loss of battery life seem to be the most significant issues faced by MacBook/Pro owners--and indeed may be related to a graphics hand-off issue between the integrated and discrete chipsets.
I also use gfxCardStatus. Most ''nice'' applications will release any discrete/NVIDIA dependency when not needed, or when quit. Firefox 6 is a different breed of problem as it will ''spin off'' dependencies and ''hijack'' the NVIDIA chip for Flash and QuickTime--but then not release it when you leave a page with those elements. This is a Firefox fail and an annoying one. A Flash solution is available called FlashFrozen. You can set it for ''auto-kill'' and anytime a Flash element is encountered, it will do exactly that. Unfortunately, it's not smart enough to wait, and you will forget you've got it enabled and wonder why Flash keeps crashing--but you will at least get better battery life by not using Flash. QuickTime has no such solution of which I'm aware. Thus, you can't keep your web browser open once you've encountered a QT element--at least if it's Firefox. Also, if you plan to use the new Google-plus Hangouts, you will be required to install two plugins that will hijack the NVIDIA chip as well.
Again, this is tangential to the random crash issue. Hoping, like everyone else here, for an update soon.
One thing I can say is nice in the face of this crashing issue--the ability to have all my work/windows brought back from the dead without loss of work. Maybe they developed this feature just to battle the random crashes?