The much anticipated Wingnuts Moto Racer [App Store] is amongst their first games for the iPhone and iPod Touch. The OpenGL 3D racing game offers accelerometer (tilt) based controls in a classic arcade-style racing game.
By "classic arcade-style" we mean that this is a racing game in which you are motivated by making checkpoints and racing against the clock. Controls are dead simple with the use of the iPhone's accelerometer (tilt control) for steering and a simple "Gas" button on the left of the screen to accelerate your motorcycle.
The iPhone's accelerometer works remarkably well for steering and requires no specific configuration. Since only tilting left and right is enough, there are no issues with compromising the screen's viewing angles.
The game offers 10 levels of impressive 3D scenery and allows you to chose from 3 different drivers (though this is just for appearance, it seems). To keep things interesting, there can be cars on the roads and belligerent bikers that try to slow you down. A "fight" button actually appears that allows you to punch the other bikers.
Overall, however, Moto Racer has a relaxed driving feel and if this appeals to you, you'll enjoy this game. Alternatively, "Kart" racing fans may be disappointed by the less frantic gameplay. This embedded YouTube video demonstrates the basic gameplay, while this video provides additional shots of scenery and cut-shots.