So the way my friends and I currently use the Apple TV is we all kind of just try to Airplay stuff from our phones and whatever randomly wins, wins. It would be cool to keep that same interaction, just with a little more structure: perhaps the videos get queued instead of all of them losing instead of one.

You can do it if the app supports it. Remember the demo earlier today of the YouTube app pausing both an iPhone and Android as the pause button was pressed? If it can share status information via wifi and the web, you can imagine a "Party Mode" or "Party Playlist" that does the same thing across multiple devices, linking them because they all see the same ChromeCast device.

If it works with YouTube Leanback this will be possible for YouTube at least. Multiple phones/tablets can hook up to the same session and queue videos to watch next.