The Doctor From Gallifrey 

There will be no full series of Doctor Who in 2012 says BBC1 controller Danny Cohen.

"There will be some episodes, but there won't be a full series, so we won't have a 13-part run [in 2012]," he said. "There'll be more episodes again in 2013, for the 50th anniversary of Doctor Who. So that's a big year."

Now Mr. Cohen said that it was because Moffat was too busy with his other hit-show, Sherlock. Moffat denied this saying on Twitter: "The scheduling of Dr Who has got NOTHING to with Sherlock. On the plus side THE BBC SPELLED MY NAME RIGHT!!!!" 

It appears that the real reason is a typical Moffat plan, probably to do with the 50th anniversary. There is no word on how many episodes will be shown in 2012 yet though.