Major Nelson has just dropped the details on how to get into the New Xbox Experience early. They're looking for a "few thousand" participants. All you've gotta do is sign up and answer a few questions (click here) to be considered for the Preview Update. Gold and Silver Xbox Live members can apply, but Gold gets first priority. If you're accepted, you'll hear from them in about a week, meaning the preview should be within the next 10-14 days.
AU: Haven't had a chance to see if it's available to Aussies... Anyone know? Share the knowledge in comments.