I posted something in the PVE forum about instance leveling. It was something like 17 instance runs per level. If they got a group together and did this they could easily achieve there level.

Or maybe they are going about it like the one guy that tagged mobs then had his guild kill them. I don't think technically that is an exploit. ~18 hours wotlk has been live. I will be interested in loggin on tonight to see what the highest level toon is on my server.