That's a good question Andy.
I've personally always thought that if a player intentionally injures another player then that player shouldn't be able to play again until the guy he injured is able to play again.
Of course, that would be impossible to enforce equitably. In this case, for example, Washington losing Ovechkin is more damaging to them than it would be to virtually any other team to lose their best player. Also, it would be very difficult to actually determine when the injured player is really ok to resume playing. It's also hard to determine intent to injure as well. I have no doubt that Ovechkin was trying to hurt the guy, that was a very dangerous play. Was he trying to break the guy's collarbone? Probably not. Although I don't think he minds what this does to his tough guy image.
In this case, it doesn't seem right that Ovechkin will sit out only two games for ending the other guy's season. But, it is pretty consistent with their punishments for similar incidents. This certainly isn't a Marty McSorley type of situation by any means.
Would NASCAR have handled a situation like this differently? I have no idea. I don't think they've shown much consistency in the past. Racing is so much more subjective though, that it is hard to draw parallels. Most on track incidents can be viewed in so many ways. Many people, myself included saw the first incident at Atlanta to be Carl Edwards's fault for coming right down into Brad's car. Others, saw it just as clearly as Brad's fault.