It seems as if Microsoft upgraded its Web servers to IIS7. This Netcraft report indicates that they made the upgrade on June 8th. You can check it out yourself by using an HTTP header viewer. It is interesting to note that they run IIS 7.0 on Windows Server 2003. I didn’t even know that there is an IIS 7 version for Win2k3. It is quite courageous to use beta software for Web servers having to cope with such a traffic load. They are not brave enough to run it on Windows Server 2008, though.