Yup, all valvers have them. They have a little (very quiet) electric motor with a magnet on it. The actual pump wheel in the water has magnetic strips on it. The motor drives the wheel round through a seperating plastic wall to isolate the motor from the water using the magnetic attraction. This is part of the anit-percolation system, and mine clogged up with crap. This didnt affect the main cooling system though.
Theyre easy to get at and you can clean them very easily. The problem is the bottom pipe under the rad gets blocked , and that needs replacing. Its a b**ch. HTH