I am probably completely wrong, but after having just finished watching episode 2, Day of the Moon, I have a new theory about the identity of River Song. This will probably be rather impossible to understand since my brain is sort of melting with a lot of different ideas and new theories, so I apologize XD
I think River is Amy's daughter (with the father probably -hopefully- being Rory).
She seems to have a spunky attitude similar to Amy's, and it just seems to fit in my mind. And now I also now think that the little girl is young!River, it makes sense. River is such a strong character, and while right now Amy is a bit young and immature, she has that attitude that shows that she is strong and will become stronger in time.
It would explain the picture of Amy holding a baby (presumably the little girl). The picture definitely looks similar to "mom holding baby for the first time in hospital" pictures I've seen. The TARDIS scanner couldn't decide if Amy was pregnant or not, going back and forth between positive and negative. This makes me think that a) she will be pregnant, and for some reason the TARDIS is detecting her future because the pregnancy is important enough for the TARDIS to know, or b) Amy is somehow seeing into an alternate universe/time stream, thus the flash of the woman with the eyepatch, and in that universe/timeline, she is pregnant.
River or young!River being in the suit would explain why River missed when shooting at the astronaut in the beginning of TIA. Why would she shoot at herself and try to aim? She had already lived this as a little girl, but she knows she has to make it all look good so she still fires, but misses on purpose. Or that she knows the suit will save herself, and expects this, thus the line "Of course not."
Now, about the girl regenerating in the end, this is where I'm wondering if the Doctor may be the father. Perhaps in another universe/timeline, Rory died in The Hungry Earth/Cold Blood, and Amy and the Doctor got together, and had River. Although, now that I think about it, that would be rather creepy if River kissed her father -full on- at the end of DotM...
But anyways, the Fish Vampire things fell threw the crack, perhaps The Silence did as well, but fell from another timeline/universe, and brought little!River with them. Perhaps they had hoped to use her for someone else, since she would be a special human-Timelord hybrid, but now were using her as a way to try to get back(?).
-ALSO-
As a second theory, what if the little girl is Jenny? She's the Doctor's daughter and it ALWAYS annoyed me that she died, Ten left, she came back to life, and we never heard about her again. What if the Silence captured her, perhaps killed her enough that she regenerated into the little girl we see. Maybe she lost her memory or didn't recognize her father's new face.
Jenny would be uber special, and that could be why The Silence are using her for... whatever they are using her for.
As for the picture, perhaps it is just a picture of her father's friend, Amy, hold her new daughter. It would explain why it was towards the back, and half-hidden. It's important enough to keep out, but not important enough to the little girl to have it front and center.
/crackpot rambling.