I love the character of River Song. Seeing as Silence in the Library was written by Steve Moffat, I'm not surprised she's coming back. It looks like they've been putting in the ground work for this new series for awhile. I had no idea that she was coming back though until I read the comments here. I'm excited. River is one of the few characters I felt emotionally invested in after just two episodes. Alex Kingston is a good actress, something to look forward to in the coming season.