Back To The Future: The Game: Episode 2: Get Tannen! (that's a lot of colons) is now available from both Telltale and Steam.
There's also a trailer, which I haven't watched because I own the game and I'm not a freakin' moron.
While I'm immensely excited as I loved the first episode, I'm a little perplexed about the sudden surprise release. There wasn't a press release and Telltale don't even have a blog up about it yet.