I don't really see why the cap would be more aerodynamic than slick skin though.
I was surprised as well. I thought for sure we would see a bunch of sly swimmers. I have often wondered about the one piece body suits though. I guess they are made out of a good fiber..but they seem like they would be more constricting.
I wonder if Headslick would be considered a illegal substance?
Personally I don't think it'd work for the amazing Michael Phelps...it would look awful..and THAT is coming from me!