Rumors have been flying around the Internet for quite some time that Rose, the first companion of the new Doctor Who, would somehow return to the show even after her character was marooned in an alternate universe at the end of season 2 in "Doomsday." This morning, as photographs of Billie Piper on the Doctor Who set have started to leak, the BBC officially confirms that Billie Piper will return in three episodes of the upcoming season, reprising her role of companion alongside of Catherine Tate's Donna and Freema Agyeman's Martha.  

John Barrowman has suggested in interviews that his Captain Jack character will also return to Doctor Who in the upcoming season, fueling rumors that there will be an all-companion episode, possibly the traditional "Doctor-light" one in which the main character is relatively absent, as in the previous episodes "Love and Monsters" and "Blink."

(Source: BBC)