The Digital Spy interview with Simon Nye, the writer of 507 Amys Choice, is here, here are the interesting bits;
This is Amy Pond choosing between The Doctor and Rory. There are 2 versions of what appears to be reality; and Amy needs to decide which is a dream and which isn't. One is five years in the future, in which Amy is pregnant and settled down with Rory. The other is the next day, and allows her to carry on exploring the universe with The Doctor.
