I think that Will has made the case rather nicely for making more folks aware that nails are employed aplenty in timber frame construction and thoughts that timber frames only employ wooden pegs is a misguided fallacy.
I am no nail expert but a thought that often passes through my mind is that generally the grain direction of one piece being nailed to another is at 90 degrees e.g. in the case of floor boards being nailed to joists. That being the case the nail has to be able to perform both with and across the grain so what would be the preferred nail orientation when nailing down floor boards ?
Is the primary difference between round pointed and square blunt that the former penetrates through the wood forcing it apart i.e. splitting it whereas the blunt square nail shears the wood effectively making its own "pre drilled" path as per NH's observations?