M. and I caught Batman: Gotham Knight last night. Six stories, ostensibly set between the first (Christian Bale) movie and the new one. Comparisons to The Animatrix are inevitable, but I think this one is a much tighter story, more concise and clever. The animation style works really well, with only one real stand-out exception that I noted, and the whole thing has a flow to it. Highly recommended. (Bonus: Crispus Allen from Gotham Central!)
And anyone who's talked to me about Batman's rogue's gallery will know which of the shorts was my favorite.