Windows Blackcomb the next windows version after Windows Windows Vista, will get Windows Vienna as codename. This doesn't indicate that there are big changes in this version, but just as before Microsoft likes to use names from cities or location with a beautiful view (vistas).
Names like Whistler were coming from a Canadian ski-place. Longhorn (codename of Windows Vista) comes from a certain saloon "Longhorn Saloon
(Info found on the Belgium newspaper "Het Laatste Nieuws")