Updated models with AMD graphics options expected in early 2017.
Apple Releases First OS X 10.11.1 El Capitan Public Beta
The new beta is available through the Software Update mechanism in the Mac App Store.
The first beta of OS X 10.11.1 introduced support for Unicode 8 and new emoji like taco, burrito, cheese wedge, hot dog, middle finger, and unicorn head. The emoji are also included in iOS 9.1, which is also in testing.
Beyond new emoji, there have been no other outward-facing changes discovered, suggesting OS X 10.11.1 is a minor update that will bring bug fixes and performance enhancements. According to Apple's release notes, the beta offers stability, compatibility, and security improvements.