No word on whether the titular character would be played by actor Matt Smith, who takes on the role of the 11th Doctor next in 2010, or David Tennant, who played the Doctor for the past four years.
Since the project is in the earliest stages, there is no guarantee that it will move from script to screen and, unless the project is fast-tracked, a release would be years away.
Tennant is definitely reprising his role as the 10th Doctor with a two-episode appearance in the spin-off series The Sarah Jane Adventures. The third installment of series -- comprised of 12 episodes -- begins airing this September.
Executive producer Russell T. Davies confirmed that Tennant is making more than a cameo appearance saying, "This is a full-on appearance for the Doctor as he and Sarah Jane face their biggest threat ever." [BBC News]