I am not sure if any school actually requires it, but it can certainly help you a bit if the grades you got were good. I would contact individual schools about the best method of sending the grades, though; some schools that I applied to didn't want official transcripts until after acceptance. They preferred that I just write them an email or send a letter telling them my grades (honor system, I guess =p).
I will be doing this. NYMC actually requested an official transcript. However, I don't think I'm going to go ahead with them. I'm sending a letter of interest with mine so I will be including the transcript with that.