Using 2 displays with full screen applications
No fun, but the answer is no. Best you can do is choose which screen your app goes full screen on, which is a minor improvement on previously. It's tricky to accomplish due to the new screens workflow, an extended desktop onto a 2nd monitor is still just one 'screen', and you want it to display 2 different screens simultaeniously - a not unreasonable request, but one which is sadly unsupported at present.