The Latest Leak of Windows 7 Beta: Ars Technica

Dec. 29:

This past weekend, Windows 7 build 7000 leaked to torrent sites. It's not the first build of Windows 7 to leak, but it definitely is the most important one so far. You see, the first 7xxx build marks the entrance of Windows 7 into beta phase (6xxx builds were pre-beta builds).

http://arstechnica.com/journals/microsoft.ars/2008/12/29/the-windows-7-build-7000-leak-and-microsofts-reaction