i'm having the same problem where the iphone gets stuck on recovery. i get the 'enjoy your jailbroken iphone' message but the phone never leaves recovery mode. shutting down/unplugging/rebooting doesn't help.
iphone 3g running 3.1.2 on a powerbook g4, os 10.4.11
i've tried a ridiculous number of times, with a variety of permutations. have re-downloaded firmware, blackra1n, have done a restore, have tried with and without holding down home/power buttons. just can't get it to work. if i re-run blackra1n while the phone still shows the recovery screen (without powering off) it crashes blackra1n.
either i'm missing something, the software is buggy or there's some common thread to the people having the same problem that i haven't discovered yet.
it's clear that blackra1n is 'talking' to my phone, but somewhere in the process the communication breaks down and i get stuck with the itunes/usb plug (recovery) icon and no jailbreak.
any ideas?