"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
Apple Seeds Fourth OS X 10.11.2 El Capitan Beta to Developers and Public Beta Testers
The fourth beta, build 15C47a, is available through the Software Update mechanism in the Mac App Store and can be downloaded through the Apple Developer Center. Public beta testers can download the beta through the Mac App Store.
We don't know exactly what improvements the 10.11.2 update will bring to OS X El Capitan, because the betas seem to be focused on under-the-hood upgrades with no apparent outward-facing changes. It’s likely to include bug fixes, security enhancements, and performance improvements to address problems that have popped up since the release of OS X 10.11.1.
Apple's release notes for OS X 10.11.2 have asked developers to focus on Networking, Graphics, Mail, Wi-Fi, Calendar, USB, Notes, Photos, and Spotlight.