I have not seen any explicit news stories or mentions here yet (outside of the normal mentions buried in the stickies) but it does appear that MS has flipped the switch and beta versions of Windows 7 (build 7000 and earlier) will begin to automatically reboot every 2 hours. If I remember right, they will stop working completely on August 15 (or was it October something).
We may want to put a "Windows 7 rebooting?" sticky so the forum isn't flooded with "why is my Windows 7 rebooting automatically???" type of threads.
We also need the mention that those using the RC or build 7100 and newer can continue to use their installations until June 1, 2010.