jamie - Sometimes "cooler" isn't always better. Sometimes the head will cool the engine too much through the infield and make the engine load up, making the engine hard to tune in order to run consistently.
Don't tune by smoke. Most racing fuels now don't produce any smoke, so it's impossible to use this as a measurement.
D Mac - Along with the threads like Casper said, the end of the plug is more conical in shape (they are sometimes called conical plugs), which is meant to fit the shape of the head button and make for a more uniform shaped combustion chamber.
kj - That post was super dope. Who was that, Jesse?
Don't feel bad about waiting for your truck..I'm pacing back and forth for mine also.
I'm twisting arms to make it to Columbus this year, cross your fingers!