"I think iPhone can read PDFs as built-in functionality.
All you need is an app which will let you transfer PDFs over in order to view them, or you can e-mail PDFs to yourself and view them from the built-in Mail app.
The app that I have which does this is called ""Air Sharing"", but I think you can get free alternatives too."
Discover is a free app similar to Air Sharing. It lets you to transfer files to another iPhone, and allows you to view a lot of different file formats on the phone.
