If you want to have a look at what the ultimate future of software-as-a-service may look like go to YouOS.  Not only is this the first glimpse of what an online OS may look like, it is also a very imaginative use of Amazon’s S3 storage services.

In terms of technology it does not get much better than this right now…a virtual dekstop running within a web browser that uses Ajax for instant interactivity and Amazon S3 for storage.