An awesome set of icons for Iphone has been released by App Bits in free download. Here you are some details about it:

Set of 48 toolbar icons for the iPhone toolbar. These buttons contain beautiful shaded portions to give added depth and to highlight icon features.
The icons in the preview to the left have effects such as gradients on them to reflect how they might look on an iPhone, but the downloaded icons have one colour with alpha, as recommended by Apple.