The latest version of Leopard (10.5.5) was just released this week. Does that mean anything for your iPhone?
Actually, it does. 10.5.5 is expected to improve sync reliability with iCal and Address Book. Plus, Time Machine will now be able to back up iPhone backups on Mac.
iCal and Address sync reliability may only be of use to those who regularly use those features, but iPhone backups on Time Machine will certainly benefit iPhone users running Leopard on their Macs.