If you're one of the lucky ones receiving an invitation to Kinect's beta testing program tonight, a word of caution before you accept: you'll be losing some of your means of communicating over Xbox Live.
Because of the 360's improved voice chat tech - or, if you're the tin-hat-wearing type, because Microsoft is crazy-paranoid about beta testers spilling the beans - anyone accepting and downloading the beta will only be able to use party and private chat with other users in the beta.
So, yes, bear that in mind!
We've also heard that because of the new avatars Kinect will be using, you'll lose any avatar marketplace purchases, as the old cloths don't fit the new characters. Presumably, these would all come back in November once they'd been re-tooled.
If anyone is in the beta and has anything to add, feel free to drop us a line!
UPDATE - Here's the official wording from the beta documentation on the loss of certain chat functionality:
While we strive to provide full compatibility with others outside of the pre-release program, there is one audio change planned that will prevent you from performing party or individual chat with people not included in the pre-release program. Note - this will be addressed when we officially release Kinect to the world. Game chat is expected to function as usual and should not be impacted by this change.