Theres a lot of people quoting IMDB as source as to who is in Doctor Who season 5, but here is why you shouldn't.
Click here. Its Doctor Who season 5, complete with the Gillian Anderson as The Rani.
Now scroll to the bottom and find the update button.
And click on it.
Now enter your Registration details, its free.
And then you can enter whatever you like into Doctor Who season 5 (or anywhere)!
Thats why no-one should ever trust IMDB with unproven facts!