Today Apple seeded a new build of OS X Lion 10.7.2 to developers. Included is a new version of iCloud, Safari and a new build for Lion itself (11C35) which is needed for the change to iCloud from MobileMe.
If you want to update, first run reversioner and then install the updated seed without restarting your system. Only restart after installing the new build.
"This pre-release version of OS X Lion 10.7.2 is being provided solely for testing iCloud and updates the public release of OS X Lion and any earlier seed of OS X Lion 10.7.2. If you installed a previous seed of OS X Lion 10.7.2, please run the included reversioner package followed by the OS X Lion 10.7.2 update without restarting your system. You should restart your system after installing the OS X Lion 10.7.2 Update. (Mac Developer Program membership is required)"
Please note that the Betas are available for developers only and can be downloaded from the Apple Dev Center.