If you are familiar with the actionScript 3 library "Tweener", you can use TweenC. We have taken a very cool library, and, well, ported it to the iPhone. It is in the beginning stages of development, but you can use it in your projects, and see some very cool effects, such as linear animation, rotation, scaling, and fade effects.

And yes, you have access to all of the easing functions like "easeInOutQuad", and "easeOutBack".
TweenC Project Downloads
TweenC Source on GoogleCode