...for a slightly early look at the NXE, the "Xbox 360 Fall Flash update". I signed up at connect.microsoft.com just a couple weeks ago, and got an email last night saying I could get the update today at 4pm CST. The official release (incomplete as it apparently will be, according to the latest OXM) is next Wednesday.

Edit: The update went fine. When I fired up the xbox it said I had an update waiting. After quickly downloading a couple things, it rebooted and downloaded some more, about 4 minutes altogether.