Whats that squeak?
 

i have a beloved 02 Impreza GX ( Don,t laugh!!) when travelling along at speed, sometimes in excess of the speed limit and the car is nicely warmed up i got this awful squealing sound which eminates from the rear o/side of the car, when i dab the brakes it stops and starts soon as i release, the wheel hub is red hot to the touch!!! ( ouch ), is this my brakes or wheel bearings or is it something much more sinister? any ideas gratefully accepted.:)