I think it was really a joke he played on the Rails guys. The original presentation is here: http://www.zedshaw.com/repository/rubyenrails2008/build/ruby... and it seems to me that it'd be easy to realize it was more or less a joke; the tone of the presentation didn't seem very serious ("Sounds like Erlang, so it's fast!").

On the other hand, maybe that's how Rails presenations typically are; I was never part of that scene.