After reading "Writing udev rules" at http://www.reactivated.net/writing_udev_rules.html, I experimeted with the /lib/udev/rules.d/90-libgpod.rules. I changed the value of "ENV{DEVTYPE}==" from "partition" to "disk". This worked for my iPod Shuffle 512 MB and iPod Mini 6GB. They're automatically mounted and RhythmBox can see them and I can resync music to them.
After reading "Writing udev rules" at http:// www.reactivated .net/writing_ udev_rules. html, I experimeted with the /lib/udev/ rules.d/ 90-libgpod. rules. I changed the value of "ENV{DEVTYPE}==" from "partition" to "disk". This worked for my iPod Shuffle 512 MB and iPod Mini 6GB. They're automatically mounted and RhythmBox can see them and I can resync music to them.