You'll need to watch all three episodes of series 2 - starting with episode 1 tonight at 8:30pm - to unlock the full ep 3 title. #Sherlock
— BBC One (@BBCOne) July 5, 2013
As you can imagine, fans outside the range of BBC television were... distraught.
Radio Times has a little more info on the clues hidden inside the series 2 episodes on British telly. And Sherlockology has even more clues. The game ends on 19-July-13, Benedict's birthday.
I have a feeling that once fans hit tumblr that what they know will be shared... but we'll see, won't we?