I've used Twitter for my personal use for several years now, but hadn't considered its value in the classroom until recently. I intend to set up a separate account for the classroom and encourage my students to follow me for additional reading and resource recommendations. I always find I'm thinking of something I'd like to share when I'm outside the classroom. This will give me that opportunity to quickly communicate with my students.
This is a resource I've drawn on in my thinking about Twitter in the classroom:
http://georgecouros.ca/blog/archives/1810