David Sparks is a lawyer who uses an iPad, Apple TV and an Airport Express combined with the TV in whatever courtroom he's in to run his Keynote for iPad/iPhone or Keynote for Mac presentations.
This really isn't very complicated and will up your game in front of your next audience. I find losing the electronic tether improves my engagement. During my last major trial, I still tethered the iPad to the projector, which was pretty awkward. Now that I've been using this wireless setup for awhile, I'm sold and don't see myself going back.
What he means by "losing the electronic tether" is that since he doesn't have to always go back to his laptop or Mac to click to the next slide he's able to stay in whatever rhythm he's in while giving talks because he's carrying his iPad with him. Which makes the iPad mini all that much more attractive.
Read how he does it.