Twitter in the classroom

I am a skeptical as to how well twitter can work in the classroom. I worry the students would forget the topic at hand and go be using it for social communication, not educational. I am sure their are probably ways to prevent this from happening. I also wonder about the amount of computer access all the students may have. I worry about the possibility of some students not having access and them being segregated out for that. As I was going through some of the tools it made me wonder. I could be a great way of keeping in touch with the students outside of class time but I also began wondering how the students parents would feel about them being on a social network. I'm sure most of the students already are but again their may be some who are not allowed this kind of networking. I have a lot of unanswered questions on how to make it work.