It was announced on Radio Two that Doctor Who will have a son!

Apparently, in order to prevent the Doctor Who series dying completely, they will need to bring in the son, to carry on the Doctors legacy. Time Lords can only regenerate 13 times and David Tennant is currently the 10th Doctor so time is running out. At the point in which the Doctor has regenerated 13 times, the son will then become the New Doctor as he will also be a Time Lord.

The son will be talked about apparently during series 3!!