It's one thing to hook your iPhone up to a video screen — it's another animal entirely to display your iPhone on a larger screen wirelessly. But that's exactly what the free Macintosh app DemoGod does: it uses a Wi-Fi connection to transmit your iPhone's screen to a Mac. The above video shows you what it looks like.
Programmer Sylvain Rebaud (who'd previously tethered iPhones to TV's with his ScreenSplitr app) built DemoGod to work in tandem with ScreenSplitr, and also borrowed a trick or two from the iPhoney screen-simulator program. Install ScreenSplitr on your jailbroken iPhone, and DemoGod on your Mac. DemoGod will locate and connect to your iPhone, and ScreenSplitr will then start broadcasting through DemoGod — and the underlying iPhoney code keeps everything in the proper perspective.
Ars Technica tested DemoGod and concluded that, while the data rate was nothing to write home about, the two apps working in tandem do exactly what they purport to do, and the quality of the result was well worth the (did we mention free?) price.