The title for Matt's final episode, the 2013 Christmas special, has been revealed and it is The Time of the Doctor. See the BBC's synopsis below:
Orbiting a quiet backwater planet, the massed forces of the universe’s deadliest species gather, drawn to a mysterious message that echoes out to the stars. And amongst them – the Doctor. Rescuing Clara from a family Christmas dinner, the Time Lord and his best friend must learn what this enigmatic signal means for his own fate and that of the universe.