Windows 7 Beta was announced at CES 2009 and you can download it now. I just did it from MSDN Subscripter downloads section.
Windows 7 home page:
http://www.microsoft.com/windows/windows-7/
Download info from the team:
http://windowsteamblog.com/blogs/windows7/archive/2009/01/07/information-on-downloading-and-installing-windows-7-beta.aspx
Steve Ballmer’s keynote:
http://www.microsoft.com/presspass/press/2009/jan09/01-07CES09PR.mspx
Keynote videos and WIndows 7 demo video:
http://www.microsoft.com/presspass/events/ces/keynote.aspx?initialVideo=Windows7Democast