Software as a Service Desktop (SaaS Desktop)
Google Apps has been the trailblazer on getting us to the sub $50/annum Office Desktop.
IBM (Lotus Live) and Microsoft (Outlook 2010) have launched their cloud based email and collaboration suites .
For companies who have reservations about entrusting all their email data to a single cloud vendor there are alternative email archiving solutions such as those provided by Liveoffice.