This is the Software Publisher's description.
Air Display not only gives you a wireless computer screen extender, but also works as a tablet input device. You can use your finger to draw directly on the screen's surface. Try it with a calculator, painting tool, or music control surface! Simple gestures allow you to operate the right mouse button and scroll wheel.
Air Display's performance is extremely responsive, employing a unique dynamic compression algorithm. On a typical Wi-Fi network, mouse cursor refreshes are indistinguishable from a wired mouse.
On Mac OS X (and soon on Windows), if your iOS device has a Retina display, you can choose to operate at normal or double resolution. On Lion, you can even enable “HiDPI mode.” HiDPI, a built-in Mac OS X feature that renders UI elements at double resolution, is absolutely stunning on a Retina display. (NOTE: the Retina MacBook Pro does not support HiDPI on external displays.)
Air Display works in both landscape and portrait configurations. Just rotate your screen, and it automatically reconfigures. When you rotate the screen, or disconnect and reconnect, your windows are automatically repositioned appropriately so you don't have to drag them back onto the Air Display screen.
You can connect to Air Display from both Mac and Windows. And because it's a universal app, it works on an iPad, iPhone, or iPod touch.
Air Display provides a virtual keyboard and mouse input on the iOS device. Air Display supports video-out to your TV or Monitor, either via Apple's AirPlay or with an appropriate adapter cable.