So I have an LG smart TV as a main TV and a newer model cheapo Sony Bluray play in the bedroom. Both of them have streaming apps built-in such as youtube and netflix.
On both of these devices I've been able to cast with the Youtube app for a few months. The Youtube app has had the "casting" button for quite some time.
So yesterday my chromecast came and I got it all setup using my tablet. I then installed the netflix app, hit the casting button and it not only saw my chromecast but saw the LG smart TV as well and I could cast directly to my TV. Went to the bedroom and turned on my Sony Bluray player and sure enough, I could cast directly to that using the mobile Netflix app.
Anyway, thought I'd mention that for folks still waiting to get their hands on a chromecast. You might already have devices that you can cast to with the youtbue and netflix apps if you at least want to play around with the functionality.
