Freebbble!

If you’re planning to showcase your app’s design in the most unclear way and from the most awkward angle possible, then this is the PSD for you.

But hey, I’ll admit that the rendering looks great and the PSD is free to use without any license involved. That’s great!

iPhone Levitation PSD is a free Mockup design resource made by Dribbble user Jérémy Paul. As far as I can tell, its license is Free for Commercial and Personal Purposes.

Helpful hint: Dribbble users are nice. If the license is unknown, it is usually because they forgot to mention it explicitly; not because they were being stingy. Ask nicely and they will probably allow you to use it.