Using Twitter as an Education Tool: Jones (2008) describes some of the uses of Twitter in academia, how to use Twitter to facilitate active learning and for storytelling. He also references an very useful article from Educause (2007), 7 Things You Should Know About Twitter, which is worth checking out as well.
When Professors Create Social Networks for Classes, Some Students See a ‘Creepy Treehouse’ provides thought provoking commentary on student reactions to professors’ use of social networking such as Twitter (Wired Campus, Aug, 2008)
Educators Test the Limits of Twitter Microblogging Tool (Ash, 2008). This provides a useful overview of Twitter and describes some ways in which pre-college teachers have used Twitter. Ash also address teacher control and cross-curricular uses of Twitter.
Twitter for Librarians: The Ultimate Guide (Laun, n.d.). Great overview of Twitter; ways to use; links to guides, studies, and articles; tools and add-ons, and libraries using Twitter.
University Used Instant Messages to Communicate After Fire (Rampell, 2008)

On mobile phones:

Schools respond to iPhone’s popularity: Campus officials roll out programs to take advantage of the iPhone’s potential as a converged, mobile learning device (Branigan, 2008). Very interesting report on Abilene Christian University’s (ACU) plans to give free iPhones or iPod touches to more than 900 incoming freshman fall 2008 as part of six-year study that ACU is doing on mobile computing. Branigan notes, "ACU already has piloted laptops, Palm handhelds, and Blackberries on a wide scale. Each was a bust, Roberts said. Laptops have limited battery life, and when flipped open, the screen creates an immediate barrier between the teacher and student in a classroom setting, he said. University officials found the Palm handhelds had connectivity problems, and Blackberries were best for eMail only."
Pen, Paper, Bookbag … iPhone? (ASCD community blog, Sept. 2008). Short blog posing question, "Can smartphones be the future of education?" with very interesting comments in response to this.
Universities must keep up (Charleston Daily Mail, Sept. 2008). Notes a number of different universities that are having students use iPhones.
Cell Phones Make Headway in Education (Kharif, 2008).

Also, anything you’re finding about using cell phones to support instruction would be interesting. I’ve heard casual mention of the very high percentage of kids who have them – maybe this is a tool we can use rather than resent.