Ed Bott, a good friend of mine, recently predicted that Windows 7 Beta bits are going to be publicly unveiled on January 13, during CES. Some late night scrounging around revealed that Windows 7 could be available sooner -- via download links slipped into the next Microsoft Action Pack Subscription quarterly update kit, which starts shipping January 5, 2009. Word internally is that the beta build was already baked a while ago, we just have to be patient.
Update (Dec 23): Microsoft has removed all mention of Windows 7 Beta.
Screenshot of MAPS kit contents. The superscript 5 means “download only”. No DVDs.