As usual, right after Apple Events, Apple today released a OS X El Capitan 10.11 GM seed build 15A282b. The latest Apple operating system coming to public September 30. Labeled as "Candidate" There may be more than one GM candidate released before it goes public.
Update: Apple's pulled the OS X 10.11 El Capitan GM, and it's no longer available for download. In the Developer Center, it's listed as "Coming Soon."
Update 2: The El Capitan GM is once again available for download. Apple has also begun sending emails to public beta testers letting them know the GM is now available for beta testers in addition to developers.
Install OS X El Capitan GM Candidate
Download FileOS X El Capitan 10.11 GM (15A282b).dmg
DataFile - Mirror