Just quick question, since I lost a track of AppStore Developer's guides&rules: wasn't there a rule that an app that is copying functionality provided in iOS wi

Just quick question, since I lost a track of AppStore Developer's guides&rules: wasn't there a rule that an app that is copying functionality provided in iOS will not be approved? Was that changed? Aside of this email app, I dont see any music players for my iPod other than the native Apple app (I see plenty of opportunities for an upgrade).