So you plug in your iPod, and Rhythmbox automatically starts up. But maybe you want GTKPod to start up, or maybe you don’t want any application to automatically launch when you attach your music player. Here’s how to control this:

Open nautilus (file browser).
Click Edit -> Preferences -> Media tab. Click the button next to “Music Player”.

This is the setting that controls what happens when you attach your MP3 player. You can choose another program from the list, choose a program that is not listed, tell it to ask you each time, or choose “Do Nothing”.

This is a Gnome feature, so it should work on any Linux distribution that is running Gnome (Fedora, Suse, Arch, Debian, etc).