IconUtility is freeware for Mac OS X.
If you create iphone&ipad icons yourself, It is harder than you expected it to be.
And it remains possible that your iphone application is not registed because of inadequate icons.

What is needed is only one image.

You need to create icons of various size, but it is troublesome task.
In such a case, IconUtility is so convenient.
IconUtility resizes an image into the correctly iPhone/iPad icon sizes.

To use it, simply drag and drop an image onto the app, then save images. IconUtility creates a folder onto your desktop that contains following appropriate images.
57×57, 114×114, 72×72, 29×29, 58×58, 50×50

generated icons

These tasks are very easy. The app will pitch a hand at creating icons instead of you.

borealkiss’s IconUtility at master – GitHub
http://github.com/borealkiss/IconUtility