"At present, there's no non-fussy way of transferring data to iPod Touch from linux machines, Ubuntu included. There is limited support in various add-ons and media players, but these are tenous at best, and quite often work with one specific version of the iPhone OS.
Just to put the above in perspective, there's not much the linux community can do to improve this without Apple's help and co-operation."
I have jailbroken my iPod Touch 2.0 and then you can actually mount it over the network with sshfs, and with libgpod4 convince rhythmbox to transfer songs. However I needed the very unlikely combination of fresh libgpod4 with rhythmbox < 0.12 (0.11.x)"