The Mix '07 website went live yesterday.  Mix '06 was a great conference but the way the '07 edition is shaping up, it will go to eleven.  As Ryan Stewart points out, WPF/E will play a very large role in this year's Mix.  Take a look at the list of sessions.  WPF/E is well represented.  I'll be presenting at Mix and I can't wait until April 30th.