As I recall from when I checked in mine yesterday, it's right behind those two 6-pin connectors just above the BT label on your photo. Extremely hard to get at, but they do exist.
Just checked - one will definately take a right angle. The other you probably have to carefully work a strait onto - it's too close to other plugs to take either a 90 degree or a 270 degree right angle.
thanks for checking that out, that's good to know. though i've got my drive situation figured out for now, that'll come in handy when SAS drives come down in price and i want to move my current sata's into externals.