The entire Apple dev center is down. That makes it impossible to download the iOS or Mac SDKs, including the iOS 7 beta. It's also not possible to provision new devices or update expired certificates. The developer forums are down too, which is somewhat frustrating since that's the only place we can discuss the still-under-NDA iOS 7.

iTunes connect appears to be up.

Apologies for those who posted this earlier. The headline gets more interesting as the outage continues.