I think this mostly affects subscription and re-occurring subscription type in app purchases. Developers often don't bother verifying other types, but it's critical for renewable subscriptions, as that server is how you check if it has been renewed.
Dealing with this for Etude right now. Just giving a free pass and logging extensively so the transactions can be audited later.<p>What's weird is that this happened immediately after Apple put Etude on the front page of the store yesterday!
I've designed my IAP such that form the moment transaction is paid till the moment it is confirmed it is "tentatively accepted", and the app works as if it was truly accepted. Should the verification later fail, the "tentatively accepted" will turn into "failed" and the related functionality will cease to work later on.<p>Payment systems outages like this are inevitable, and design a billing system without handling outages gracefully is just inviting trouble.<p>On a related note, I am open to licensing the tech (both iOS code and the backend server) to anyone who is interested.
Perhaps this is related to <a href="http://news.ycombinator.com/item?id=3019783" rel="nofollow">http://news.ycombinator.com/item?id=3019783</a> as an outage to fix the problem system-wide? Cross fingers.