In case any of you missed it, panics and oopses are written to /dev/mtd2, so it might help debug the reboots.

You can also disable reboot on panic and panic on oops by writing 0 to /proc/sys/kernel/panic and /proc/sys/kernel/panic_on_oops. This might require removing of battery to fix, but will help find out if the reboots are due to kernel panic/oops, or due to some higher level or watchdog timer.