X-Plane is the premier flight simulator for Mac, Windows and Linux computers as well as iOS. It's accurate enough to have received FAA certification for some phases of flight training, and TUAW editor Steve Sande even mentioned seeing airline pilots waiting to get on their aircraft "playing" with X-Plane 9 on their iPhones.
Today, the creators of X-Plane have released a brand new version for iOS devices. X-Plane 10 is free, but if you want additional planes there are a few in-app purchases.
The free version lets you fly a Cessna 172, and gives you access to all the scenery areas including The Grand Canyon, Seattle, Alaska, Hawaii and the mountains of Austria. The graphics are first rate. You can look freely around the cockpit by dragging your finger. A tap gives you views outside the plane from multiple angles. Like the version that runs on the Mac, you can set equipment failures and really horrible weather to fly in. Cities are rendered with 3D buildings that sparkle at night. X-Plane lets you decide the time of day you are going to fly in.
Planes you can add as purchases include an F-22 Raptor, an F-4 Phantom and seven more aircraft including the Airbus A320 jetliner. With Game Center, you can participate in multi-player adventures. A built-in flight school will teach you about the basics of flying.