The fine folks at teehanlax.com have created a nice GUI template for iPad, which can be customized in Photoshop. You can download it from here.
And if you can bear some ads then this blog post has a nice list of 7 such GUI packs.
Mobisoft Infotech LLC, Houston, Texas. All Rights Reserved.
Discover Mobility by reaching us @ our offices in Pune (India), Houston (USA), Ontario (Canada), Melbourne (Australia), Jurong West (Singapore)