And honestly, if Google had any intention of having generally open access to it, they would have started with DLNA support, which would have allowed many phones to push to it out of the box. Instead expect it to stay heavily locked down and to only provide good support for getting users on to Chrome and Google Play.
Chromecast's API hasn't been finalized and their are huge warnings all over the documentation telling you to not release an app until the API is final. Apple has never released an API and has actively tried to stop things like Airfoil from working.
I'm successfully pushing local content to my Chromecast. The developer in question was using an undocumented API. If you use the documented APIs, things work just fine.
And honestly, if Google had any intention of having generally open access to it, they would have started with DLNA support, which would have allowed many phones to push to it out of the box. Instead expect it to stay heavily locked down and to only provide good support for getting users on to Chrome and Google Play.