Now Available via Software Update:
iSync lets you manage your contacts, calendars, To Do lists, and Safari bookmarks across multiple Mac OS X computers and devices (such as an iSync-compatible mobile phone, Palm OS device, or iPod), so you always have your most current information with you. To sync a Palm OS device, you need to install the iSync Palm Conduit version 1.2 or later.
iSync 1.5 adds support for more devices such as the latest Sony Ericsson and Motorola phones. For more information about supported devices and connectivity requirements, visit www.apple.com/isync.
Before you install iSync 1.5, you must install iCal 1.5.2 or later. To download the latest version of iCal, visit www.apple.com/ical, or use Software Update (in System Preferences) to install the latest version.
If you are using Mac OS X version 10.3 and plan to synchronize a Bluetooth mobile phone, you need to have Bluetooth version 1.5 or later installed. To download the latest version, use Software Update (in System Preferences). If you have an earlier version of Mac OS X, visit www.apple.com/isync to download the appropriate Bluetooth version.
Details about the new iSync release are available here: http://www.apple.com/support/downloads/isync_readme.html