DFU mode problem
After installed 3.0 I crashed my phone and needed to restore it using DFU mode. Be warned that OS X 1.5.6 has a bug in the USB driver that causes DFU mode node to work with iTunes (leading to a "waiting for iPod" message forever). You need to used an older OS X, another OS, or install the IOUSBFamily driver (kext -- kernel extension) from an older OS release.
I hope this helps somebody. I had a hard time finding out what to do.
This was a bug in Mac OS X 10.5.6. Just update to 10.5.7 and you'll be fine.