The Smartest Kids in the World: And How They Got That Way by Amanda Ripley
Even though we home school, I found a lot of fascinating stuff in this book that looks at public education in the U.S. and in three countries whose 15-year-olds test much higher than ours do: South Korea, Finland, and Poland. Some things that matter: rigor, high expectations, well-trained teachers. Some things that don't matter so much: money, high-tech gadgetry, sports programs. There's much more to it than that, of course. The tone is hopeful and doesn't condemn American education, just gives some good ideas. And even though the three featured countries test high, the author shows the limitations of their schools, as well. (South Korea is particularly ... uh, interesting. Yes, let's go with that adjective.) That's a pretty lame summary, but I loved this book and highly recommend it to everyone.
By the way, at least 2/3 of my kids said to me while I was reading this, "Oh, you're reading a book about us!" They are so funny.