iTunes 4.8 is the latest installment from Apple and now includes new Music Store features and support for transferring contacts and calendars from your computer to your iPod (requires Mac OS X version 10.4 on your computer).
Syncing of contacts and calendars requires Mac OS X 10.4, otherwise, iTunes 4.8 continues to work on earlier versions of Mac OS X.
Download your copy of iTunes 4.8 now!
This is an excerpt from the Apple iTunes site that seems to suggest that syncing calendars and contacts to an iPod using iTunes 4.8 requires Mac OS X 10.4. We have no confirmation on this at present. Any feedback is welcomed.