Late to the party.....
St DS8's school 6-12th, the classes are gender separated in 7th and 8th. When they first did this there was an uproar, but grades and test scores have proven that it works.
I read in a Gifted Child Today book on Mathematics in one study that the gender separation really worked-- for the girls. The middle school girls in general asked many more questions about the topic before starting their work, and asked deeper and more abstract questions. The boys jumped right to the problems and would only ask questions if they were having trouble. The girls grades really catapulted upward, many many more A's. The boys grades in this study actually decreased...
Obviously there are many factors at work here... but interesting nonetheless.
