Cloud abilities of desktop vritualization today (March 2011):
There are arguments against the Cloud licensing models with respect Microsoft licensing availability to be compliant virtualizing applications or OS in the desktop/laptop.
Here is how it goes:
•Remote Desktop (Terminal) Services: offers application presentation for all virtualized applications
•Desktop Operating Systems comparable capabilities to VDA, VECD, MED-V, MDOP: Can be acquired through traditionial licensing models, and can be managed in the Cloud must have Software Assurance (SA) on the desktop and subscription to appropriate desktop virtualization technology.
OEM windows, SA and Windows Upgrade, are typical concerns of overpaying for licensing titles, unfortunately the licensing model does not seem to be changing anytime soon
Obviously non of the above is now offered with Office 365, but through OnDemand Licensing from Long View