There is a reason why they decided to call it Project 2007. Seems that they are slipping the release until 2007 corresponding to the slip in Vista. Some more information here:
http://www.microsoftmonitor.com/archives/014509.html
Since Vista most likely will require a new PC due to heavy hardware requirement, I guess they are thinking that most office users (read corporate IT) would hold off on an upgrade to office until the Vista dust settles. Or at least that is what I think they may be thinking.
