Apple sent out an e-mail early Saturday morning to alert developers that the Developer Center and Developer Web site would be offline briefly starting at 6:00 P.M. PDT on Saturday August 17th, 2013 to undergo scheduled maintenance.

Apple does not go into details about what will be getting worked on Saturday evening. The Developer Center was recently hacked into and caused a three-week outage in which Apple needed to re-build the Web site’s security. It's unknown if this has something to do with it or not.

Apple gave Developers an entire month of free membership to make up for the three weeks that the Apple Developer Center was down, so the extension would make up for tonight's outage as well.

Seeing as how the maintenance will be brief Saturday, it doesn’t look like the downtime will cause that much inconvenience for Apple developers. You can keep an eye on Apple's System Status Indicator to see the status of Apple's services.