I also recall seeing a "legend" of this but that was many years ago.

One purple star is mod. Three is admin. The red star is a leftover from many years ago when a single payment got you a lifetime "membership" but now you must pay an annual membership and that gets you the yellow jersey. The eagle is a Sheldon Brown special award to a handful of very righteous recipients.

I think that's correct and I think that covers our bases, but I am sure others can chime in to correct me if not.