I saw this on io9. Sounds like Tennant has completed his stint as the Tenth Doctor and Matt Smith is set to start filming in a month. There are a few vague details about the regeneration and more below...
"A few tricks up our sleeve"? Perhaps something to do with 10.5? Another weird Fourth Doctor/Watcher type of regeneration? Maybe he trips over a brick face down and when he's flipped over he turns into Matt Smith?
Doctor Who:
David Tennant has finished filming his stint as the time-traveling weirdo whom we all love. And he was heard to remark something on the set about being like "an uncool Spider-Man." Did he mean that the Doctor was climbing walls or kissing upside-down in his final scenes? Or was he referring to one of the many comics where Spidey drops acid and has weird Spider-themed head trips? Or something else? Also, apparently Matt Smith starts filming in about a month, which means only one thing — more set reports. (Well, it also means they'll be making some television, I suppose.)
Also, Russell T. Davies tells the BBC the next special episode, "The Waters Of Mars," will air in November-ish. And he hints that the Tennant-Smith regeneration may be "a lot more complicated" than just one Doctor turning into the other — "We've got a lot more tricks up our sleeve." [Planet Gallifrey]
"A few tricks up our sleeve"? Perhaps something to do with 10.5? Another weird Fourth Doctor/Watcher type of regeneration? Maybe he trips over a brick face down and when he's flipped over he turns into Matt Smith?