Also, a somewhat undocumented feature, which may be of interest if you still plan to use iPodLinux.
If you hold PLAY whilst booting, the Rockbox bootloader looks for a file called linux.bin in the root of your FAT32 partition.
As far as I know this is still true, though I haven't had an iPod for quite some time. I used to triple boot Apple's firmware, Rockbox and iPL via Rockbox's bootloader.