I was just rewatching "Silence in the Library"/"Forest of the Dead," and, to quote the 10th Doctor himself:
"Oh! I'm thick! Look at me, I'm old and thick! Head's too full of stuff, I need a bigger head!"
River knows the Doctor's real name in "Silence in the Library." But in this episode, "The Name of the Doctor," the Doctor's name will be (supposedly) finally revealed. But, we were promised a post-Library River in this episode.
See what I'm getting at?
This is the episode where The Doctor is supposed to reveal his name for the first time. Yet River already knows it long before this episode.
This isn't just the culmination of everything that Steven Moffat's been working on since "The Eleventh Hour." This is everything going back to "Silence in the Library."