...but you're on a Mac with Leopard 10.5.6 that kills DFU mode, you may be in luck. If your iPod or iPhone is already jailbroken, just use PwnageTool to create a custom 2.1.1 IPSW. Then, Option-click "Restore" in iTunes and choose the custom firmware you made. No DFU mode necessary. Worked like a charm for me.