Cell Phones: Tools for Learning? Or Weapons of Mass Distraction?

The other day I received an email from a recent graduate of our Teacher Preparation Program. He was helping out in a school at home, since Commencement is long past for us, but classes are still going in K-12 schools. He saw this sign hanging up at a high school teacher's door:

With thanks to my (anonymous) (former) student for allowing me to post this...

Knowing that I am fascinated by educational technology, and the way we often use consumer technologies as educational technologies in schools, this prompted a question from him:

Hmmm...I use my phone to find a lot of information, more than my computer even. Maybe though in study hall high school kids "waste" too much time on it? Or should study hall be their choice of time once in high school? Your time, use it as you want without disrupting the class?