The muchly anticipated book, The Writer's Tale: The Final Chapter, has been reviewed on SFX, with a lovely article spilling some yummy facts about what could have happened! Check them out here. My favourite could-be is:
11. A line was cut from the scene where the Doctor talks to Wilf on the Vinvocci spaceship. He would have explained that he “was half-human back in 1999 for a couple of days” (a reference to the Paul McGann movie).