U.S. News & World Report has an article on the use of Twitter in the classroom. The author provides several examples of how faculty are using the social networking/microblogging site to enhance communication both in and outside of class. The article is available online.

Not familiar with Twitter? Twitter permits microblogging or the posting of 140 character messages (known as "tweets") to others on the site who have signed up to "follow" you. In turn, you select those that you wish to follow. Many professional associations, including Educause, have Twitter accounts. Even some professional journals have Twitter accounts.

The Educause Learning Initiative has a a short introduction (pdf) to Twitter: "7 Things You Should Know About....Twitter."