Availability of the Nexus 7 to Canadians is "in the coming weeks" according to Hugo Barra.
Android 4.3 is rolling out to the 2012 Nexus 7, Nexus 10, Nexus 4 as well as Galaxy Nexus (yakju) starting today.
What the ChromeCast does right compared to the Nexus Q was that the hardware is small and inconspicuous, and is OS agnostic unlike a competitor like Apple TV which only works with iOS. BUt the most impressive part of the ChromeCast is that you get this capability for a measly $35 dollars.
All in all a good day for Google given the intimate setting for in person media and less frenzy than Google I/O.