I'll keep most of this under a cut, but the spoilers aren't major ones if you've kept up with who's signed what contract already. But there are a couple of major ones here, but nothing that's not come from the Who camp themselves.
The series episode titles are:
1. Partners in Crime
2. The Fires of Pompeii
3. Planet of the Ood
4. The Sontaran Stratagem
5. The Poison Sky
6. The Doctors Daughter
7. The Unicorn & The Wasp
8. Silence in the Library
9. River's Run
10. Midnight
11. Turn Left
12. TBA (The title of Ep12 is being kept secret as it gives to much away)
13. Journey's End
The sixth episode is the one that will probably make most people's ears prick up. Apparently there's a twist, but David Tennant says: “We get to see the Doctor’s daughter, played by the Doctor’s daughter.” (A reference to actress Georgia Moffett, the real life daughter of former Doctor Who star Peter Davison)
He also said: "And episode 10 is maybe creepy in a way that we’ve not done before. That’s probably the most psychologically scary we’ve ever done.”
Billie Piper's contracted for three episodes and it appears that the series finale will be through the last three episodes as in last series. Rumors have it that something happens to the Doctor and companions Rose, Martha, Donna, Mickey, Jackie, Jack and Sarah-Jane all end up trying to save him.
Also rumored to be back in that finale - the Angelophile pleasing, utterly awesome Harriet Jones MP for Flydale North. I love love this character. Her return would make sense. The Doctor messed up the timeline when he screwed her out of office after she destroyed the alien invaders in the Christmas Invasion, meaning "Harold Saxon" could take power. With the end of the Master, him slaughtering the cabinet, there's a power vacuum where Harriet SHOULD have been in power for 12 years and ushering in Britain's new Golden Age. Will she step back into power and thus fix what the Doctor broke by trying to play vengeful god?
U.N.I.T. are major players this series and as revealed in Torchwood, Martha is their medical liaison.
Catherine Tate on Donna not fancying the Doctor: “She knows he’s an alien and she knows he’s got two hearts. She don’t want to know what else he’s doubling up on. I think that’s a fair point.”
Apparently they've "toned down" Donna since her original appearance to try and make her more sympathetic, although she still isn't immune to 'emotional outbursts'. (Presumably shouting a lot.)
Apparently Simon Pegg was in the audience of the press launch, along with Bernard Cribbins and Elizabeth Sladen, who are both appearing in the series. Could this mean he is appearing a second time?
And speaking of the legend that is Bernard Cribbins, it appears after his appearance in the Christmas special, he's to be a recurring role - playing Donna's grandfather. Apparently this was in the trailer, but I musta missed that part.
Guest stars: Alex Kingston, Colin Salmon, Sarah Lancashire, Felicity Kendal, Lesley Sharp, Lindsey Coulson, Fenella Woolgar, Tim McInnerny, Peter Capaldi, Phil Davis, Bernard Cribbins, Tracey Childs, and keeping it in the family Georgia Moffett and David Troughton.
Oh, and going by previews, the rumors that Davros is back along with the Daleks do seem to be gaining weight.