This is a really fantastic book on why gaming is important. I'm about half way through, and I've learned a lot. It's really given me a different perspective on why gaming isn't a waste of time, and how it makes our lives richer, and makes us better people. I highly recommend it to anyone, gamer or not.
If you don't read the book (which you probably won't) at least check out this TED presentation that the author did. She makes a lot of the same points she makes in the book, although much more abbreviated. It's inspiring stuff.