I found a nice video that explains how front kick really works. Paul also shows how to chance the kick to hit difference surface and stuff.
I usually hit people with front kick in sparring at least few times during each workout, but don't hurt them. I guess the last part should be a thrust. He calls it a hybrid way of kicking.

Here is a youtube clip.

http://www.youtube.com/watch?v=SYEiym-kuRY