I agree with alot of the things said by Todd; but to be honest, I am completely against the legalization of Marijuana. If it were to ever be legalized, it would end up under the complete control of our government. With the government in control, they can basically regulate the distribution of it as much as they want. They can even make laws that prevent people from growing their own plants and thus force the user to buy their overpriced version of Marijuana. By legalizing Marijuana you basically tell them, "here, take the last bit of hope we have from preventing a complete corporate society in which that one little green paper dictates our lives."
Assuming that this were to become a reality, this wouldn't change anything. As it is right now, you can not smoke, possess, or grow marijuana. If the government legalized marijuana for the purpose of profit, it would still serve to benefit pot smokers, they could legally carry and smoke marijuana. Even if the government sought to exploit smokers by selling pot at very high prices, one could still just buy from an illegal dealer, which they must do already, only difference being that after their illegal purchase they could smoke/possess it freely.