How can I sync with an iPod Nano 6G?
Apparently Apple borked linux support with Nano 6g, and it's proven difficult to hack the music database to allow access to non-iTunes apps.
https://bugzilla.gnome.org/show_bug.cgi?id=631006
http://ubuntuforums.org/showthread.php?t=1611473
I had the same problem and fixed it with the sledgehammer method:
Virtual Windows system + ITunes.
I installed virtualbox 4 and set up a Windows XP. To use the USB drivers I installed the Oracle Expansion Pack. The Licence changes from OSE (Open Source Edition) to PUEL (Personal Use and Evaluation License).
Plugin the Ipod to your Ubuntu System. Start the VM with Windows and Itunes. Under "Devices" in the Virtual Box select your ipod nano. Windows and Itunes will find it.
I also shared my music-library with a virtualbox shared folder and mountet it under windows.
This works for me but I am unhappy with the situation too.
I just tried the solution, syzygy proposed: I installed the Spotify client preview for Linux and synced my iPod Nano 6G with it. So far it works.
Be aware that first Spotify wipes the iPod and then gives you the possibility to sync playlists. Spotify doesn't have the same comfort as Rhythmbox or Banshee yet, but I am happy that there is finally a solution for the iPod Nano 6G.
This works with a free account.