After penning Day Two and Day Four of Torchwood: Children of Earth and Episode 9, "The Gathering", of Miracle Day, scriptwriter John Fay has apparently been asked to write for Doctor Who.
According to his official CV, "John is currently writing an episode of Doctor Who", having just returned from the US during production on Torchwood.
Series 6 is all but finalised, so Fay's episode will likely be slated for Series 7, production of which is expected to begin over the summer, starting with the upcoming Christmas special. Of course, as anyone who has read Russell T Davies' The Writer's Tale can explain, writing an episode doesn't necessarily mean inclusion for the series. For instance, Neil Gaiman's "The Doctor's Wife" was originally scheduled for last year.
Moffat could always reject Fay's script, so calling him a writer for Series 7 is premature. But with the excellent work he put into Children of Earth, as well as his other accomplishments in Primeval and the thrilling Coronation Street, it's safe to say that his script will be more than satisfactory.