A timeline (or more accurately, timelines) of events in River Song's and The Doctor's meetings. (Click for bigger)
While the trailer doesn't show much. The big news here is there is going to be a "Doctor Who" video game. There have been adventure games recently, but this one is going to be different somehow. Not much information is available, other than that players will "take on the role of the Doctor and River Song as they travel across time and space to save the earth." Sounds good to me. "Doctor Who: The Eternity Clock" is set to release in early 2012.