So, it looks like Valve is planning a big Christmas event. A whole bunch of Steam games have gotten holiday-themed achievements added...including Jurassic Park.
Just thought that was worth mentioning. I think it's pretty cool that Telltale's taking more of a part in the Steam community.
Also, not sure if anyone on the Telltale Team can answer this, but did you have to actually update the game for this (i.e.: adding new lines), or is it just simply throwing in a new achievement?
EDIT: Poker Night at the Inventory and Puzzle Agent 2 have Christmas achievements as well!