
I didn't see a dedicated thread for the next special, so I made one.
After the credits finished rolling for "Planet of the Dead", there was a preview for the next special, and it gave a title: "The Waters of Mars". The preview can be seen here.
Unfortunately, we won't get to see it until "November-ish", according to Russell T. Davies.
From Wikipedia:
The story is set on Marshttp://en.wikipedia.org/wiki/The_Waters_of_Mars#cite_note-7 and the Doctor will be joined by a new companion named Adelaide, played by Lindsay Duncan. Producer Nikki Wilson (née Smith) described the character as "the Doctor's cleverest and most strong-minded companion yet."
Wikipedia
I think that's enough to get things started. Thoughts anyone?