The developer portal went down July 18 due to a security breach, and after some time released a statement regarding the security situation. In an interesting turn, the person responsible went public, and 25 year-old Ibrahim Balic explained that he had not only posted a bug, but then use the exploit, which apparently prompted Apple to close everything down until a fix was applied.
Since then Apple has been putting services back online a few at a time. As TechCrunch reports, it started "...with certificates, identifiers and profiles, as well as its developer forums, bug reporter and libraries. It then brought back software downloads, including its iOS 7, OS X Mavericks and Xcode 5 betas and now, it has also restored access program renewals and enrollment, as well as Xcode Automatic Configuration."
Given the amount of down time, Apple has extended developer memberships (normally lasting one year) by one month.
Of course this comes at a tough time, as developers have been working feverishly to update their iOS apps for the radical new changes in iOS 7. Here's hoping Apple learns something from all this.