Twitter is an amazing tool for keeping students informed as well as providing accessibility to the teacher outside of the classroom.

My Take

What makes Twitter such a valuable teaching tool is the diversity of how it can be used. Mainly as a mode of mutual communication, it can be used for additional "office" hours, reminders and announcements, professional collaboration, running a live tweet hashtag stream of classroom learning as it's taking place, not to mention using the tool as a meta-communication tool- allowing students to create fictional accounts relating to characters of study (i.e. "John Proctor" from the Crucible) and create group tweeting experiences that enhance the traditional learning approach in the classroom. (for other ideas, see: http://www.teachhub.com/50-ways-use-twitter-classroom)