From Apple’s App Store rules:
5.6 Apps cannot use Push Notifications to send advertising, promotions, or direct marketing of any kind
In practice, this rule is blatantly disregarded by thousands of apps that routinely violate it by sending promotional push notifications. It has become a widespread standard practice, even among small developers with lapses in judgment.
It’s not hard to figure out why this rule isn’t enforced — it’s mostly unenforceable. A violation isn’t likely to be caught by Apple’s reviewers in the few minutes they spend with each app.
Apple would need some sort of violation-reporting mechanism on each notification, which would add ugly clutter to the UI and would require a staff at Apple to go through each report and reliably act on abuses, neither of which Apple is ever likely to do.
And this afternoon, Apple itself violated this rule:
Regardless of the cause, this is clearly a promotion, will annoy thousands or millions of people, and is in direct violation of the least-enforced rule in the App Store.
If Apple won’t enforce its own standards against spamming and annoying customers — which really isn’t good enough — the least they can do is practice the rules themselves and be a good example.