I am Ghanaian working on a similar idea for different purpose. In Ghana(and most of "third world") , where the average user cannot afford a computer but will be able to afford a few hours of internet access - this idea would be very useful. I am part of an NGO: Ghanathink(http://www.ghanathink.org) that is currently in the design stages of such a concept. The original idea was from Paa Kwesi a Ghanaian student at Yale Univ. Our architecture builds on the oceanstore project from berkeley for data storage. We basically write the open-source desktop environment that the user sees.
Now if only we had the resources that Intel had ...