Yes, t.A.T.u. is back, not with music (although they are rumored to be working with Trevor Horn again), but as an animated movie. Found it by accidentally while looking for information about the new Wong Kar Wai film 2046.
So, there's not much info out yet (comes out November in Japan and UK).
Here's t.A.T.u. Paragate
Part of this film (only the opening credits as rumored on the net) will be directed by the guy who did Cowboy Bebop which is one of the few anime shows worth watching from a few years ago.