Apple's Developer portal was shut down last week following an attempt to steal user credentials from the site. Since then, a Turkish security researcher has claimed responsibility. Apple has now updated the security on the portal and updated a number of systems, but not everything is up and running yet.
In order to let people know what's going on, Apple has created a status page so that developers and others can see what systems are operating and which are offline. Not much is running at the moment which means developers are denied access to the latest release of Mavericks and iOS 7.
Apple Developer System Status [Apple]