There has been a lot of work going on behind the scenes for a good few months now to develop an updated Wiindows Desktop licencing scheme to make it easier for organisations to implement centrally hosted virtualized desktop environments.  Microsoft have finally released details of the new licencing scheme called Vista Enterprise Centralized Desktop (VECD) which covers off everything from normal PCs accessing centrally hosted virtualized desktops, thin clients accessing centrally hosted virtualized desktops, to "diskless" PCs booting off centralized OS images.

Check out the press release here http://www.microsoft.com/presspass/features/2007/apr07/04-02WVenterprise.mspx and look for more info coming out over the next few days.