Microaoft announced to day that they will split TechEd US 2008 in two: TechEd Developers and TechEd IT. They did that in Europe a couple of years ago because they couldn't find venues large enough to accomodate so many attendees. Space is no proble in US conference centers but I think it's a smart decision to split it anyway.
More info here: http://www.microsoft.com/events/teched
