I was thinking about this not but an hour ago. The only problem is deploying a recursive server solution to maximize uptime and reduce load on any one server. The software's the easy part, the hardware's the hard part.
I mean obviously this would be for some Data Center as an additional part to there hosting, this would scale horizontally.
Also how to do this at similar prices compared to AppEngine and with similar levels of support (maybe due to anonymous payments attracting shady characters there might be even a slightly increased rate of abuses for spam etc.) is something more difficult than just deploying that and starting to earn BTC.
Well app engine just raised there datastore so you can do it competitive there cause we be paying in bitcoins and you can really get more precision when pricing. Also for spam I mean you would probably have to monitor it.
It could definitely be doable. And horizontal scaling makes a hell of a lot more sense than vertical. This would be an epic thing to have.