http://www.youtube.com/watch?v=-Eynl4tmqGk Well first off you're going to notice that the credits list Moffat as the writer but Gaiman explains on his blog:
It’s credited to Steven Moffat as writer, but then, they’ve credited me on the box as writer of The Name of the Doctor which he wrote and I didn’t, so there you go.
I'm actually really sad to the see the River Song storyline over and done with since it had tons of potential and was one of the coolest aspects of Doctor Who for me personally. That kind of story planning is something you rarely find outside of comic books. There are supposedly ten (or possibly nine) more minisodes featuring River and the Doctor on dates, but we'll have to wait to see if they make it out onto the net.