I don't think they are Keith. They seem to be on highly inclined (about 55 degrees) but not polar orbits. See this site, and select "GPS Operational" from "Satellites in Orbit". They aren't polar but they are certainly not geosynchronous.

There is a system of satellites for a Motorola satellite phone system called Iridium. These are indeed in polar orbits. They are notable as the shape of the satellite reflective antennae means that at certain points in their orbit they focus sunlight on the earth. So for a very short time, a few seconds, they can be very bright indeed, as bright as magnitude -8, so around 50 times as bright as the planet Venus. You can get a prediction of when and where you can see them from this site, enter your own location and it will tell you the times of the bright Iridium flares, and other interesting things such as passes of the International Space Station. You need a clear sky about an hour after sunset or an hour before sunrise, less than this and the sky is too bright, more and the sun isn't shining on teh satellite as it is in the earth's shadow.