Yes, I agree that sites like Twitter and Facebook are good platforms for social change. Twitter can help raise awareness for charities, and help organize groups that wish to create a way to bring about positive change, all without being in the same room, city, or even country. On the other hand, Twitter also helps create buzz about topics that are thoughtless, unintelligent, or unnecessary. Twitter in some cases becomes an outlet for blabbering on about everyday topics, such as: this movie stinks, I hate mustard, When is Captain Crunch: The Movie the coming out?
It has also helped change the way people think about social interactions. For example, sites such as Facebook is where virtually all of your friends, family, coworkers, acquaintances and even enemies in the same room. You are able to chat with them, send them a message, post a comment, "like", "poke", and more. You are literally able to do this for as many friends as you have on your Facebook. Instead of picking up the phone and calling someone; one on one, the mentality is to interact over Facebook.
This shift in face-to-face interaction is both a good and bad thing. For one thing it allows separated family and friends to stay in touch and stay connected. On the other hand it has reduced the need for social interaction with already close family and friends. For example, I post stuff on my sisters Facebook wall even when she is in the other room as me.
Social media sites like twitter have also help create a place where regular people can interact with their favourite musicians, comedians or politicians. This has created a huge social change. In the past these stars where unreachable now talking with them is only @ symbol away. This has created a feeling of connectedness, on a global scale.
The level of convenience social media offer will continue to change social interaction. Social media sites will keep finding ways to link us to the rest of the world only making it more easy and accessible.