Apple has released Mac OS update to developers purely to use for testing the iCloud support.
Apple had announced the iCloud service for streaming and syncing all content on Apple devices a while back. The service will start for Mac and iOS later in autumn, but with latest Mac OS X 10.7.2 release sent to developers, iCloud has been implemented in it to begin the developer testing.
The version does not appear to address any bugs or issues in Mac OS X Lion but instead adds iCloud to the Mail, Contacts & Calendars control panel. From there users will be able to choose what they want to be synced to the cloud and manage storage and backups.
Since Apple has badged the developer release as 10.7.2, it’s likely that Mac OS X Lion 10.7.1 will be an update for the rest of public with bug fixes and tweaks.