Speaking to io9, Whithouse said that:
The thing about Being Human is that Being Human takes place in our world. That's what we've always tried to do. There are no plans for werewolves and vampires being revealed to the people of the world in Being Human, because the moment that happens, it stops being in our world and becomes in a different world. And with Doctor Who, Doctor Who exists in the Doctor Who world in that the world knows about the existence of aliens, they get invaded every Christmas. So that's a very different world. Being Human is much more rooted in our world. So I don't think it could happen.There you go. Done. Crushed. All my hopes and dreams over.
All kidding aside, it's a bit sad though that these two worlds may never come together in one extraordinary story. I can very well imagine Matt Smith's Doctor meeting up with, let's say Mitchell, and have the two of them size each other up.
Or George and Rory, hitting it off to get a beer or something, and Amy basically just hanging out with Annie and Nina. Maybe Amy could finally give Annie a well deserved new wardrobe. Just saying.
I'm still going to dream for a while. Plus, Whithouse never said a categoric NO, just that he doesn't think that it could happen . . . grasping at straws, grasping at straws.