Panther's Mail and Address Book applications can use WebDAV to synchronize contacts and mail with Exchange 2000 and 2003 servers. However, there are a couple of problems with it (which I'm following
here). The biggest is that if you installed iSync 1.3 before you installed Panther, you won't have the library you need to sync with Exchange.
John Perry
figured out that you can extract ExchangeConduit.bundle from the iSync installed on Panther CD 2, then put it in /System -> Library -> SyncServices. That made my sync work, and it seems to be working still.