Oh, here's some (rather lame) insider info for you guys: I have a black belt in Taekwondo and have broken many boards in my day. The yell or "kiap" in Korean that Taekwondo people always do while attacking really helps you get more energy (force), and the boards, thus, break much easier. I think Jon, Al, & Jon did it, but the others did not. Also, the stance is very important, as you want a solid base (= power) behind your punch. I also agree with everything LG said.
And, just some nitpicky terminology stuff:
Dojo & Sensei (school & teacher, respectively) are Japanese and are used in Karate. In Korean and for Taekwondo, it's Dojang & Sabumnim.