I just quickly wanted to share something I think others may find useful if they are having problems getting a rockbox iPod to work under Ubuntu with Rhythmbox.

Basically the problem is that, though your iPod has a different firmware on it, it is still detected by Gnome as a standard iPod. This causes all sorts of problems with applications treating your Rockbox iPod as the standard iPod that only accepts aac and a database.

The quick fix that I found was as follows:

Firstly we need to backup the file we are about to change, press alt+f2 and then paste the following into the box:
gksu cp /usr/share/hal/fdi/information/10freedesktop/10-usb-music-players.fdi /usr/share/hal/fdi/information/10freedesktop/10-usb-music-players.fdi.backup

We now need to open up the file that tells Gnome (and more specifically a program called HAL) how to dectect the hardware and what it is capable of. Press alt+f2 and then paste the following into the box:
gksu gedit /usr/share/hal/fdi/information/10freedesktop/10-usb-music-players.fdi

There will be, near the top, a piece of text that looks like this:
<match key="info.category" string="storage">
<!-- Apple iPod - TODO: use USB ids to determine exact output formats -->
<match key="storage.vendor" contains="Apple">
<match key="storage.model" contains="iPod">
<addset key="portable_audio_player.access_method.protocols " type="strlist">storage</addset>
<addset key="portable_audio_player.access_method.protocols " type="strlist">ipod</addset>
<append key="info.capabilities" type="strlist">portable_audio_player</append>
<addset key="portable_audio_player.output_formats" type="strlist">audio/aac</addset>
<merge key="storage.requires_eject" type="bool">true</merge>
</match>
</match>

You need to change it too look like this:
<match key="info.category" string="storage">
<!-- Apple iPod - TODO: use USB ids to determine exact output formats -->
<match key="storage.vendor" contains="Apple">
<match key="storage.model" contains="iPod">
<append key="info.capabilities" type="strlist">portable_audio_player</append>
<merge key="info.category" type="string">portable_audio_player</merge>
<merge key="portable_audio_player.type" type="string">generic</merge>
<merge key="portable_audio_player.access_method" type="string">storage</merge>
<merge key="portable_audio_player.storage_device" type="copy_property">info.udi</merge>
<append key="portable_audio_player.output_formats" type="strlist">audio/mpeg</append>
<append key="portable_audio_player.output_formats" type="strlist">audio/x-ms-wma</append>
<append key="portable_audio_player.output_formats" type="strlist">application/ogg</append>
<append key="portable_audio_player.input_formats" type="strlist">audio/x-wav</append>
<merge key="storage.requires_eject" type="bool">true</merge>
</match>
</match>

Now just save the file and close. That's it, now you should be able to use Rhythmbox or Banshee to upload media to your iPod.