Scenester, its nothing really special. Game Room is just the shell, and you buy the games and deck out your room. Like Family Game Night.
It's not Gold exclusive (at least I've seen no confirmation), because PC gaming is usable too as it's cross-platform and Live Windows doesnt have Gold tier.
Also, it's gonna start retro, but it will eventually get to our era.
Game Room is basically where they are gonna dump all those ports that are on XBLA right now, so they dont clog it up.