Apple began rolling out updates to its .Mac service over the weekend presumably to add new Mac OS X 10.5-specific features. The update requires Mac OS X 10.4.10, and Mac OS X 10.3.9 or earlier users will no longer have the ability to sync calendars with Mac OS X 10.4 users.
As of Monday morning, .Mac sync services were still temporarily unavailable or operating in a limited capacity for all users. Additional information is available at the Apple Support and Apple Discussion Web sites.
.Mac will offer several Leopard-specific features including the ability to synchronize application and system preferences, Mail Notes, Dock items, and Dashboard widget preferences between multiple Macs.