Apple today released iCal 1.5.5, an update to its popular calendar application. Version 1.5.5 includes improvements in iSync synchronization on Macs running Mac OS X v10.2 (Jaguar). The update is available via the Mac OS X Software Update preference pane. Last month, Apple released iCal 1.5.4, which includes security enhancements to help protect your Mac when importing events with alarms that open files or applications.