A pple has released an update for iCal, bringing the calendar app to version 1.5.5. According to the brief notes in Mac OS Xis Software Update control panel, the update "includes improvements in iSync synchronization on computers running Mac OS X version 10.2."
The download weighs in at 7 MB, and you can find it in Software Update. You can also download the update directly from the iCal Web site.