The blog entry from the manager of developer teams at Microsoft cites several reasons why Vista has been delayed, among which are "the code is too complicated", "poor organizational decision-making", and "ignorance as to a proper estimation of software schedules".
Maybe this is just another attempt by Microsoft to release press (indirectly) explaining to us why Vista is late. I wonder if he received any money for posting this. Probably not because the original post has now been deleted.
The original post from the manager's site has been pulled down and this might indicate that someone from PR at Microsoft caught wind of it and issued an immediate order to the employee (although the Microsoft blogger claims this isn't so, "This was originally posted a week ago, and yanked of my own volition"). Thanks to wonderful Internet technology, the original page has been mirrored by Digg and can be found here.
Microsoft's projects that Vista will be officially released in January 2006 (here) but we'll have to wait and see if this comes true. Until then, there is the public beta which you can find here.