Apple is very clear as to how a developer can use its push notification service. It’s there to add functionality, and that’s it. No spam, no ads, no messing around. They’re very clear :
5.5 Apps that use Push Notifications to send unsolicited messages [...]
5.6 Apps cannot use Push Notifications to send advertising, promotions, or direct marketing of any kind
It seems that the folks from Glee, or actually Smule, as they are the ones who developeed Glee’s top-ranking paid Karaoke app, couldn’t contain themselves. Today, they surrendered to the temptation, and have begun a promotion using push notifications to their very large user base. Thereby, putting themselves on the spot.
As much as we can complain about Apple’s rulings, regulating push notifications makes a lot of sense. If you agree to be interrupted by an app, it must be for a good reason. For example, when someone sends you an instant message. Or, maybe to remind you to pick up your kids from school. Definitely not when a developer tries to get you to randomly spend more time in their app, on some sort of promotion or even cross-promoting their other apps. Imagine if the 100 apps you have installed started sending you advertisements. It would make your phone unusable.
This sort of unsolicited advertising shouldn’t happen. Also, Smule is not the only one to do it. However, for such a high profile developer, they should know better. Now we’ll see if they make it until the morning.