Sherlock Holmes 2, which we're guessing will have a nice eccentric subtitle like The Curious Incident of the Third Dimension (because by 2011 everything will be 3D), now has a release date, and it's December 16, 2011.
That puts it up against Alvin and the Chipmunks 3D (told you everything would be 3D by then) and Mission: Impossible IV (which, OK, isn't. Yet.) - so the question is whether one of those films will blink. After all, all three would appear to be aiming at either the family market or the action market or a combination of the two, and somebody might choose to jump forward a week or fall back. At the moment, the week before sees the release of Hugo Cabret in 3D, which will do well for the kids' market if there's any justice, and the week after has Spielberg's The Adventures of Tintin: The Secret of the Unicorn (in 3D).
With Sherlock Holmes 2 still in pre-production, we don't know much about the plot. It's fair to say that Robert Downey Jr, Jude Law and Guy Ritchie will all be back, and that Moriarty will appear / be alluded to somewhere, but that's about all we have at present.