I presume you mean it is NOT moving. Get a multimeter or a 12v bulb with short lengths of wire attached and see if there is power at the connector which connects to the motor. If there is power there then it is the motor, if there is no power then it is the fuse, switch or wiring.
From your handbook find out which fuse is for the rear wiper. Swap the relevant fuse for one of the others of a similar size to see if its the fuse that's gone, remember to swap it back afterwards.
Chances are it would be the motor that's gone on a 10 year old car....