What if you limited people to writing in a domain specific language: one that ran distributed on this infrastructure? How would that make it different than folding at home, for example?
"“Monthly Uptime Percentage” is calculated by subtracting from 100% the percentage of minutes during the month in which Amazon EC2 or Amazon EBS, as applicable, was in the state of “Region Unavailable.” Monthly Uptime Percentage measurements exclude downtime resulting directly or indirectly from any Amazon EC2 SLA Exclusion (defined below)."
Amazon EC2 SLA Exclusions... (v) that result from failures of individual instances or volumes not attributable to Region Unavailability
Presumably if you're using a cloud hosted in people's basements, if someone's basement server dies, you'd just pick one from someone else's basement, so this model could provide better availability than AWS.