Well MSFT invested a ton on Longhorn and then scrapped it. Vista is just a different face on NT.
http://www.informationweek.com/news/showArticle.jhtml?articleID=189501075
True, but Vista really is a beast of a different stripe. It will be released, and it should be very interesting to see what MSFT cooked up. I'm expecting something several orders better than their past operating systems.
Longhorn was an ambitious transitional OS. Kind of like Apple's Copland OS before Apple scrapped it and went with NeXT's code base and BSD.
My only concern with MSFT is if they'll be expanding their new licensing model in Vista.