Here's the deal with Mullen's PR/Social Influences Dept. when I was there: Suzanne Daly made the program great and now she's gone. You work on whatever accounts they choose and mostly do clipping and media lists if you're unlucky. That's about it. Unless someone awesome like VP Michael Bourne gives you projects. DO THEM. The skills you learn are highly applicable. Otherwise, you get almost no job/career training. I was also stuck with very slow-moving accounts - other interns had more responsibility because they had better accounts. On the plus side, everyone is really nice and there's free coffee. Befriend the other interns and learn from them. Meet with your supervisor and keep a journal of your assignments if you want to negotiate for better projects. I wish I had done this.
Get good accounts and you'll do great - otherwise consider asking your supervisor for additional accounts so that you'll get some real experience. Learning Vocus is not a good enough reason to intern here.