Jonathan Strahan (ed) The Starry Rift (New York: Viking, Penguin), 2008.
Jonathan Strahan’s The Starry Rift is a really excellent YA sf collection, for 12 yrs and up. It contains thought provoking stories by some of the best writers in the field and they are all science fiction. There isn’t a fantasy story in the lot. I know that sounds odd, but you'd be surprised at how many sf and fantasy collections for kids I have upstairs which contain very little science fiction.
As I can't say what I want to say about this book without major spoilers, I'm going to delay my comments for about a month.