Nate Heagy wrote up 5 common mistakes developers make in marketing their apps for iOS - one being that you can't just say your app is for iOS, you need to list the specific devices (iPod touch, iPhone, etc.).
Another requirement Apple has is that you are not allowed to use white Apple products in your advertisements or videos. It's odd since Apple obviously has no problem using them in their ads.
I know. You're shocked. Apple apparently has double standards for their developers. /sarcasm.
Read all 5 Nate items or follow his link to Apple's new marketing and advertising guidelines PDF released in September of 2012.