Whenever my system BSODs (or reboots*) it will put an Information entry in the system log saying something like "the system rebooted from a bugcheck". Why they didn't make it a critical error instead of an information item is beyond me, but that's how it is.
*For some reason, the reboot button on my system doesn't work, and I don't like to toggle the power to reboot it; since it only seems to BSOD when I'm away, it might as well reboot on its own (gotta keep RC5 going; no downtime allowed).