I THINK the guy's name was Bill. I also think Eric said his final peak was in October.
Now that they have started numbering, they have to go with it. I finished before the 10,000th finisher, but my finish was only about a month earlier, so obviously I'm aware that WAY more than 10,000 people finished before me. Therefore, to me the number isn't important, its the accomplishment and each individual's personal experience to themselves.
I don't think they should put the number on the certificates (going forward), but like Tim says, the AMC should keep the statistics, as they have done. Leaving the number off the certificate keeps the accomplishment on the same level as anyone who does it. Hopefully, people will be able to hike these mountains forever, and when the 1,000,000th person completes it, the AMC will still be around to announce that they have reached that milestone. When that happens, it will still be the same accomplishment. Maybe the AMC could think of adding an extra cost type of item if people wanted numbers on there certificates. (I know that is unlikely) If the AMC is unsure of what to do, at the very least they should probably make the first sentence of the reply mailing to say: "Dear Joe Hiker, Congratulations, you are the #th registered member of AMC's 4000-footer club."