It really does exist, and today we admitted it at the Professional Developer's Conference in Los Angeles. See http://www.microsoft.com/presspass/events/pdc/default.mspx for all the PDC-related news, and the refocused Windows Team Blog at http://windowsteamblog.com/ for more specifics on Windows 7. (If you missed it, there was also a posting about Windows Vista and Server 2008 SP2 last week too.)
There is also an "Engineering Windows 7" blog at http://blogs.msdn.com/e7/ that offers interesting details from the Windows 7 engineering processes.
I'm just glad there's now all kinds of pre-beta software for me to be using again. Things were too boring after the Windows Vista and Server 2008 releases - what challenge is there in using RTM software :-)
We are hard at work on a new version of the Microsoft Deployment Toolkit to support Windows 7. More details on that will be disclosed at the TechEd EMEA conference next week in Barcelona.