These mostly come from Apple's Human Interface Guidelines (<a href="http://developer.apple.com/library/ios/#documentation/UserExperience/Conceptual/MobileHIG/Introduction/Introduction.html" rel="nofollow">http://developer.apple.com/library/ios/#documentation/UserEx...</a>) but people seem to overlook them. Very cool to see an app that got feedback from Apple and did something new and compelling with it.