If you haven't already seen it, we set up an "event" on Facebook to represent the real-life Mix:UK event. Get yourself invited by visiting the event page on Facebook and clicking on "Add to my events" just under the Mix logo on the right-hand side of the page.
Then indicate that you're attending from the options that are displayed.
Of course, if you want to come to the real mix event head on over to the registration page at www.microsoft.com/uk/mix07, there aren't many places left!
There is also my Silverlight Mix07 Sample Site at http://silverlightuk.blogspot.com/2007/08/silverlight-mix-uk-sample-site-first.html
Thanks Chris. Great stuff, very interesting to see this.