It sort of bugged me that I could get minecraft to launch in Steam, but then it immediately stopped recognizing that I was playing the game. Anyway, if you're interested in getting the overlay (shift + tab) to work in Minecraft and for your status to show you in game, you can follow the instructions in this relatively easy video:
http://www.youtube.com/watch?v=Mr_iZUC8mKE&

Happy mining!