If your iPhone App icon isn’t appearing on your phone, but works fine on the simulator, it may be a problem with the way you’ve saved your Icon.png file:

Blank iPhone App icon

I had this problem, until I chose to “show” the extension of the Icon.png file when I saved it from within Preview.  Once I’d done this, re-saved the image and added it back to the project, the Icon appeared on the phone!  Bizarre, but it works!