DrtWho_The_Time_of_the_Doctor_promo
The final outing of current Doctor Matt Smith (with the inclusion of John Hurts's incarnation, I will not attempt to number him), Time of the Doctor will see the Time Lord face his ultimate challenge on Trenzalore. Cybermen, the Silence, Daleks, and Weeping Angels have been confirmed to appear as enemies and the story will close with the arrival of Peter Capaldi as the new Doctor.

Moffat has stated that The Time of the Doctor will wrap up several plot threads that have been left dangling over the past few years... which I will believe when I see. It will be interesting for the program to resolve the Doctor's 'final battle' which he has already seen the outcome of in Name of the Doctor, especially considering that David Tennant's Doctor simply said he didn't want to go there. With the shattering of the time lines around the Time War on Gallifrey, anything seems to be possible.

(I am mainly putting this up because I saw people were coming to my blog looking for information on this upcoming episode)