Agreed! The one thing that worries me about this is underpowered hardware. If they made the UI not suck (read: not take seconds to respond to button presses) then I'll be all over this. It'll end up being what Google TV should have been.
Exactly. In truth, there is nothing preventing you from playing Crysis (other than a terrible response time and a poor quality video stream) on this with nothing else but this and a wireless keyboard/mouse. This is the true dumb terminal. The developers SDK is probably more about connecting devices or having them communicate with the chromecast rather than being an app repository.
The more I think about it, the more I hope this is where they going with this. To borrow a very damaged phrase, this might as much about the cloud/virtual computing as it is about streaming and music.