Starting this Tuesday (May 12th) we will release up to ten test updates to PCs running the Windows 7 RC in order to verify our ability to deliver and manage updating of Windows 7 in certain real-life scenarios. These updates do not deliver any new features or fixes. This is the second set of test updates we’ve released to test the updating mechanism for Windows 7 - the first set were released on February 24. For more information, see this post on the Microsoft Update Blog.