I saw that wreck as it happened. Khane had a great run going and Allmendinger came down the track to block him. Two errors were committed. Kahne went too far down the track and into the grass, he would have actually been better off if he had backed out of the gas, but he might not have figured his team mate was going to run him off the track. Allmendinger is Kahne's team mate, team mates should help each other, not try to wreck each other. I understand that blocking is part of racing. I also understand the concept of team mates helping each other gain position, maybe Allmendinger doesn't understand that concept. If that's the case, then he really needs to be in a single car organization.
I do not think NASCAR needs to step in and regulate blocking. This is something that needs to be handled by the teams and car owners.