Prerequisite for iPhone UI design?

I received a request from a client to design him an application for iPhone and possible iPad.

I will be provided with the page wireframes of the application, but still, I’m wondering are there any technical details that I need to consider while designing the user interface?

I’m not using those modern and trendy gadgets, so I thought I should ask here.

From: http://developer.apple.com/ipad/sdk/index.html

iOS Human Interface Guidelines

Yep, that’s the same resource I just stumbled upon, which means I’m on the right track. Thanks!