A few days back we reported the release of Amarok 2.4 a.k.a Slipstream for Maverick and Natty users (both Ubuntu and Kubuntu). As I wrote earlier it now supports iPhone 3G and possibly newer devices. It has updated its PPA.
You can install Amarok 2.4 in Ubuntu using KDE backports PPA. You can add the PPA by opening the terminal and typing the following:
sudo add-apt-repository ppa:kubuntu-ppa/backports
sudo apt-get update
sudo apt-get install amarok