I attended the DevDays 2006 and my overall impression was: cool. Allthough some of the sessions I attended weren't good (or actually, were very bad), the overall feeling is good and I picked up on some great stuff. Meeting up with some smart people is also a good addition to attending the sessions.
The most impressive session I attended was Scott Guthrie
Another great session was Anko Duizer on MSF. I think that because of the movement IBM is making with RUP (gradually pulling it more and more to Java), Microsoft has brought their way of developing software to market supported by the Team System/Team Foudation suite. Anko talked about MSF and the rules used to ensure a good software development process. That was interesting stuff...
For those who attended: the best rule I heard was "Don't shake the Jell-O".