I've got an Ubuntu desktop and, yes, an Apple Powerbook. With the latter, I can sync music to the iPhone with (of course) iTunes. But though the free and open source Amarok could sync music with the older iPhones, the new version 3 iPhone software makes this impossible. The recommended way to do it is using a virtual machine running MS Windows, which I use Mac and Linux to avoid!
Apple - please offer a solution for Free Software syncing.