From Major Nelson:

Looking for official details on the Fall Dashboard update? Check out the Newsflash (or the complete list of new features) just posted on Xbox.com then look for the update to head your way after 0200 PT Tuesday morning (What time is that in my time zone?.)  If this whole ‘update’ thing is new to you, don’t worry…it’s quick, free and painless. Next time you login into Xbox Live you’ll get prompted to receive the update…it’s that easy. There is no way to force the update (and, regardless of what you have heard, it's not geographical based.) So sit back and relax and it get ready for the update sometime after 0200 PT Tuesday morning, October 31st.

Can you say, "Ready for HD-DVD" or "Ready for WMP11"? Nice work.