Microsoft intends to release on Tuesday (24/03), test updates for Windows 7 beta. That'll be five updates, tops.

According to Microsoft Update Blog, updates will not fix bugs, nor add new features, at first they will only replace system files with files of the current version. Then you ask why. The purpose of these updates is to test the system infrastructure and verify Microsoft's ability to send and manage Windows 7 updates, to ensure that when updates are really needed, everything will be fine.