[Lenny]

Haven't a clue about that, but I've just found out the script is by Steven Moffat who has written, amongst other things, several Doctor Who episodes: The Empty Child and The Doctor Dances, The Girl in the Fireplace and Blink. He's also doing a two-parter for series four. He also wrote the 1999 Comic Relief Dr. Who episode - Doctor Who and the Curse of the Fatal Death.

So we can rest assured that the script should be rather good.