It's certainly an interesting idea.  I could definitely see an MMO using this concept, kind of like a next generation Second Life leveraging crypto currency instead of virtual currency.

I bet you could take advantage of a pool using the data from shares to generate terrain and content using procedural generation.  Might just be the next big thing in free games (I.E. the game is free, and the subscription is paid through game client mining on a pool)  Certainly no small effort involved in making such a thing, but it's not impossible.