How to recover your iPhone from Safe Mode
Until recently I didn't know that Jailbroken iPhones had a Safe Mode for when SpringBoard crashes, but the other day my iPhone suddenly restarted and presented me with these screens:
When in Safe Mode certain functions are disabled, but you can easily restore your iPhone to normal Operational Mode by either:
Tapping the Restart button in the Safe Mode Notification Dialog
... or:
By holding down the Sleep / Wake Button for a few seconds, dragging your finger along the "slide to power off" slider, waiting until the iPhone turns off, then pressing the Sleep / Wake Button for a few seconds until it turns on again.