A short while back, Digg hosted a link to this crashed iPhone showing single user mode. In that case, the error message stated that the iPhone couldn't "exec /bin/sh for single user: No such file or directory." Now that the iPhone has been thoroughly hacked, this error has evolved somewhat.
Last night, TUAW friend DrunkDwarf crashed his iPhone but since he'd actually installed a copy of /bin/sh his error was somewhat different. Instead of complaining that it couldn't find /bin/sh, his iPhone simply... ran it. Not that this was much better news. Without a keyboard and no way to attach one, DrunkDwarf was a bit out of luck. He ended up having to do a restore.