MezzoLew, that's a nice bike and very good price. I think that is one of the later models, the seat clamp is the updated version and as far as I can tell from the photo, the fork end clamp design is the later one too but I could be wrong.
I believe the Bike Friday was in existence well before the Mezzo but design concept of a rear swinging triangle and rigid main frame tube is nothing new and appears on other folding bikes, Birdy being one of the most well known.