He wrote an article about it. The only thing that remains from the original project is the idea and the name.
Not that that's bad, of course. The original idea was very specific and did a lot of unnecessary magic, really. ESR's big contribution to fetchmail was to hand off that type of handling to other processes that were always going to exist and did that sort of thing better anyway. You could say he made it more Unix-y. :-)
Wade.