Macrumors posted a story that the sixth beta of OS X 10.11 El Capitan has been released to developers

The update is available through the software update mechanism in the Mac App Store and through the Apple Developer Center. While early betas introduced minor design changes and features, the last few betas have focused on under-the-hood performance improvements and bug fixes to optimize OS X El Capitan ahead of its public release. OS X El Capitan builds on the features introduced with OS X Yosemite, focusing on improving performance and user experience. Behind-the-scenes improvements in El Capitan have made a number of apps and processes on the Mac much faster, and the introduction of Metal makes system-level graphics rendering 40 percent more efficient.

  Apple Seeds Sixth OS X 10.11 El Capitan Beta to Developers