The icon must be provided in both 57x57 and 512x512 versions. These can be optimized for each resolution, but should be essentially identical.
We prefer clean, simple icons. Tweetie is an excellent example.
The icon should ideally reflect both the GIFT and LIST aspects of the app.
Icon should ideally contain no words.
The icon should ideally be designed pre-glossed. This is where the corner beveling and any shine/gloss are incorporated into the icon and not added by the iPhone.
Icon should have a non-black, non-transparent background and a clearly defined border.
Finally - please don't just stick some stockphoto gift box on an abstract background. We could do that ourselves :)
Bad v Good: http://www.artofadambetts.com/uriconiswrong/
Good tips and examples: http://pixelresort.com/blog/iphone-…practises/