Within this post you will find complete GUI kits and stencils, iPhone GUI elements and PSDs and finally a collection of the best icon-sets perfectly suited for the iPhone…
Right up to date with the iPad GUI PSD we mentioned a little while ago, so looks like that’s the best current reference to point your Photoshop-using artist friends at.
How about Apps-on: Post-It notes for your iPhone design? (h/t: iPhoneFlow!)
Or just download some iPad & iPhone Sketch Paper PDFs.
Or try iPhone Wireframe Kit – Google Docs online.
And here’s a newer roundup: 11 UI Kits for iPhone and iPad Development!
These Keynote/Powerpoint templates look interestlng: Keynotopia