I think this idea has some serious flaws. In fact, I believe the project will fail because people don't want their CPUs being used for mining. Period. They don't want adds, but they want to mine Cryptos for someone else even less. Just look at the recent headlines about crypto-currency mining adds. I know they aren't the same. However, when people hear about this, they are going to equate it with the same thing. If it ever makes it mainstream, their will be major backlash.
That's what I thought at first. Then, I realized that current advertisers and websites are already quite intrusive. They used data from your search habits, and they insert files into your browser (cookies) that keep track of your activities. I think that Oyster's CPU-borrowing can become commonplace in the same way that cookies have.
Looked pretty awsome, that you could choose like that. 
