What I would really like them to make hackable is the protocol. Anyone knows what the chromecast is using? It'd be awesome to create "Chromecast" servers that can receive video and browser tabs wirelessly.
One of the articles stated it uses WebRTC (video conferencing) for showing the Chrome tab. I wish Google has made it more open and supported standards like DLNA and Miracast and WiDi myself. Better off with Netgear at this point.