I've never been a big fan of Twitter, and find the instant gratification of the tweets to be used mostly for information I'd have been happier not knowing. I've read a few blogs, some from classmates, that have begun to change my mind, but then I find things that remind me why I really don't care for it overall.
One blog we were introduced in class listed 60 Inspiring Examples of Twitter in the Classroom, but there were many I felt took the personal interaction, or responsibility out and replaced it with 140 characters.
I don't think it's asking too much for students to arrive on time, or for a teacher to have set office hours that can be flexible as needed. Even for the things I could use Twitter for, I don't see how a forum discussion is any harder. Students and teachers can still leave comments for each other, and other people can read them. I've yet to see a school that doesn't have email for the faculty, so sending an email versus sending tweet means it's one more thing to check every day.
I like the idea of keeping parents updated, or making notifications easy to see since people who don't have a Twitter account can still follow a twitter feed and receive texts on their phone. But I don't see how making a classroom even more instantaneous is helping the students learn respect for someone else's ideas, or fostering patience in waiting their turn. I see the instant gratification making people more antsy to be heard, right now, and it frustrates me.
I definitely don't like the idea of Twitter to build reading and writing skills. I like the idea of technology in building the skills, but Twitter and texting are not the way to go. I think students flipping back to a Twitter account or feed while in class is taking time away from them learning directly from each other, or from the teacher. Even if trying an exercise in learning to be concise, there is a word count feature on almost every word processor application, or even barring that - you hand write a sentence or two and manually count the words.
Don't get me wrong, the applications for Twitter in a school system are growing and very useful in staying in touch with the community when instant conversation is necessary - I just don't think asking the students to interact with it in the classroom is the best option, for me.