Neil Gaiman, who won a Hugo Award for his first Doctor Who script The Doctor’s Wife and then announced at the Awards ceremony that he was writing a second, will have that second episode produced and shown as the next-to-the-last episode of Season 7 of the revamped Doctor Who series, which means that it should air (in both the U.K. and the U.S.) in the spring of 2013.
 
When Gaiman first announced that he was writing a second Doctor Who script (see "Neil Gaiman Writing Another 'Doctor Who' Episode"), neither he nor anyone else was sure whether it would be produced for Season 7 or put off until Season 8.  Gaiman’s first Doctor Who scenario, The Doctor’s Wife, was originally slated for Season 5, but for budgetary reasons--in order to get the episode made properly--it was put off until Season 6.  Now the Doctor Who TV site in England has confirmed that Gaiman’s episode will be the seventh aired in 2013.  It is one of three episodes out of eight that has not yet been filmed, but it is definitely on the schedule.