I believe that to a certain extend social media can actully help social change. I say this only because, yes social media is helping a lot by publisising all the need and groups that you can help support threw facebook, twitter, my space and all social media's. You can help by being a part of them and showing your interest in each type of thing that the group is trying to accomplish. But by saying that you "like" or that you are "apart of a group" it only shows that you agree with it but it doesnt actully show that you are doing somthing and that you will do somthing to try and change whatever the cause may be.
So like I said, social media is a great way to show everyone that need that are out there and how they need the help but it doesnt mean that they will help and actully make a real social change.