Got this from a very reliable source.

This weekend, the comeback episodes of two fan-favourite series -- Battlestar Galactica and Doctor Who -- come with a historical cross-over. First, Starbuck's return is explained, not by her being a Cylon, but by a timely intervention by a certain Time Lord. After saving the maverick blonde, he proceeds to tell her where, after all, is this "Earth" place. He then takes her there to see it, where they discover Martha Jones is really the Last Cylon! The two of them then run back to Galactica for help, leading directly into the events of the BSG season 3 finale...

Highlights: Jack Harkness (John Barrowman) sets up a sevensome with Gaius Baltar (James Callis), #6 (Tricia Helfer), #3 (Lucy Lawless), #9 (Freema Agyeman), Starbuck (Kattee Sackhoff) and a Viper (Clint Eastwood).