What about "royalties" for Soup for supplying the original answer? (Just looking out for your intellectual property there, Tomato!)
Rob (as usual) gives sound advice but I believe he meant to say the "rear caliper" is cable operated. You can buy a tool to spin it back in to free it up, then you activate the hand brake a couple of times and it self adjusts forward. My '07 suffered the same symptoms - basically setting the parking brake gave your arm some mild exercise but other than that it did nothing.
Though it's true that most of your braking is done with the front, I definitely felt improved braking with the rears freed up. (Yes, if the rear calipers aren't grabbing when you set the parking brake, they aren't doing anything for you down the road either.)
Be sure to post back on how you made out.