Article about MLA listing how tweets should be cited and the controversy about it. Also interesting fact: did you know that the Library of Congress has been archiving every public tweet since 2006?
Part of the University of Wisconson's "Writer's Handbook." This is a page of links re: APA, Chicago, MLA and other documentation styles as well as links on numbered references and quoting/paraphrasing. The rest of "The Writers Handbook" is linked in the left navbar.