Scoble sheds some light on the Longhorn restart:

Either way, I'm glad the story is getting out. The short view is that last year we threw out the code that had been written for Longhorn and started over with a fresh code base (they restarted with Windows Server 2003's codebase, by the way). Then they started checking in features one at a time, albeit with higher quality bars. It was a very painful time. I had been sold on how cool Longhorn was going to be too, and last year I couldn't really say much as they rebuilt the entire product.

Well, that's not far enough back, IMHO. Windows started being a mess with NT 4.0, when they decided to move the graphics drivers into the kernel (and ushering in an era of blue screens related to that decision). It went downhill with the full bore integration of everything with everything else. What this decision does, IMHO, is delay the day of reckoning for the "big ball of mud" a couple of years. They'll be right back to their 2004 state, because they haven't actually dealt with the real problem yet.

And believe me, I know a big ball of mud when I see one. One of the things that our team has been working on is untangling the core Smalltalk image for VW into components. It was built as one big ball of mud from the start, and it's not easy to untangle. We know that's a problem, and are addressing it. If untangling VW is more complex than I'd like, imagine what untangling the mass of dependencies in Windows is going to look like.