There is an app called SplashTop that works in conjunction with a SplashTop Website that you log into that allows you to walk around your classroom and actually be "behind" the students and watching what they are doing without losing the ability to work on the Smartboard or white board.
This app allows the teacher to walk around with his/her iPad and control the computer that is hooked up to the projector or Smartboard. As the teacher becomes more mobile. the temptation to do what is NOT supposed to be done lessens, and I believe that kids would pay attention more and stay on task.
We actually purchased the SplashTop app for each teacher, so the ability to do this is already here! Again, a username and account has to be created and logged in to, but once that is done, and you log in to the app on your iPad, control of your Desktop computer is just a touch away:)!