As JEP alluded, it's just identifying members of the forum who are engaged on a regular basis, helpful and who appear to have a good level of knowledge about our service. Typically they're fans of the service, although they can be critical at times as well. They are not compensated, although we may in the future send our champions some tokens of our appreciation like T-shirts or USB drives and the like.
One of the mods emailed me once telling me he wanted to make me a champion but I would have to stop telling people how much better the other forum is. At the time, I didn't see any advantage to being a champion but I could always use a T-shirt. :)