It would make sense for Amazon to raise the price rather than disallowing it (specifically, because enforcing a prohibition on activity would cost Amazon money, but setting the price to be at least marginally more expensive than Amazon's expected minimal-effort realizable gain from using the GPU instances themselves would make Amazon money.)
This is both the worst and best thing to happen to Bitcoin.
It's good because more and more people are learning about Bitcoin. It's never going to stand a chance without mindshare (ignoring any other problems it has).
It's bad because when this bubble bursts, the resulting backlash from people "investing" in it (instead of using it as a currency) is going to put people off.
That's just on Gox. On BTC China it's touched over $1000 USD in Yuan and on Bitstamp it's only $675. The global average is over $800 already. The USD only average is quite a bit below that.
Is it actually possible to sell BTC held in a random wallet and withdraw the proceeds as USD? I'm not familiar with the intricacies of the various exchanges, and am wondering if it is truly a convertible currency. (Assume that selling ~500 BTC would not move the market.)
You need to watch the other US exchanges as well, not just MtGox. It's basically impossible to get USD from MtGox right now, making it a very poor benchmark for the actual exchange rate.
