Integration seems seamless. The Nautilus file manager accesses the tracks, playlists and apps, while RhythmBox can integrate with the contents much like iTunes can (although it cannot play back any DRMed files you might have ...). This has been tested using the latest hardware, and the latest firmware.
In my opinion Ubuntu is fast becoming the most user-friendly and versatile of the Linux distros, and offering iPhone/iPod touch support only makes it even more user-friendly.
This should help open up Linux to a whole new audience.