I wish I had a fix for you, but I don't. I just tried to sync my iPod for the first time after upgrading to OS X 10.3.9 and loading iTunes 4.8 and it won't show up in iTunes or on the finder. It charges just fine and Apple Profiler knows that it is connected. A similar thing happened to me in February (you can look up the thread at http://discussions.info.apple.com/webx?7@@.68a547f3/136 . Last time Apple posted a patch within a week or so. Hopefully they will do the same this time. Meanwhile, it is certainly frustrating.
Brad