i guess it is so obvious now that no one has posted this but for the noobs.... note: iPhone 4S only
just airplay to an apple tv and video mirror then output the atv to a device that can record - like tivo, dvr etc. you can also use a video out cable on the iPad [1 and 2] now
not sure if the cable works on the iPhone 4S as I havent tested that myself
its clunky but there is no other way i can see atm.