The Nano is formatted with hfsplus (used under MacOSX earlier) hence when plugged under Ubuntu Linux is mounted read-only. To have it mounted read-write you need to plug it on Mac and then issue this command
$ diskutil disableJournal /Volumes/Somebody’s\ iPod/
this will remove the journal from the HFS+ filesystem, and now Linux will mount it read-write. Then use whichever application to manage your songs.
