An article in the most recent Baseline states that you will come to love dead zones, meaning places where wireless signals are blocked by design. Among the places that are suggested as dead zones: conference rooms, classrooms, and public transportation---the very places that conventional wisdom says ought to be the first places you deploy wireless technologies.
I don't agree with the premise of the article, that companies will seek out ways to create dead zones. Culture is a more effective deterrent for inappropriate behavior than technology. In many ways, I see this as the analog to the problem we face with technology that forces transparency. If you want my attention in a meeting or class, make it relevant and interesting. Don't rely on locks and jamming technology to get my attention.
The concern over cheating is real, although I have to admit I've never worried about it much. Most of the classrooms I've taught in at BYU would be difficult to use a handheld device in without the proctor being able to see. I also design my tests to be open book, short answer or essay questions with answers based on analysis rather than memorization. Those kinds of tests are much more difficult to cheat on than a multiple choice test, but they're harder to grade.