I was speaking to a Microsoft rep who said at the time that the XNA kits were - at the time (little less than a month ago) - what they were still sending out to developers... http://i.min.us/ikuQPO.jpg http://i.min.us/ikuSXW.jpg
It's just an updated xbox360 slim devkit with a new sidecar. I don't see how this has anything to do with an xbox720.