120 Beautiful iPhone UI Icons
Eddit.com has designed a nice custom icon library targeted at iPhone app developers. The icons are suitable for use in the Tab Bar and Tool Bar, but would also integrate nicely into any iPhoneized website. The set includes 120 png icons and a sample app for browsing the set. Note: this is a commercial set and will set you back $69 as of the date of this post.
Download from eddit.com