"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
Apple Seeds First Beta of iOS 10.3.2 to Developers
Registered developers can download the iOS 10.3.2 update from the Apple Developer Center or over-the-air with the proper configuration profile installed.
We don't yet know what features or improvements are coming in iOS 10.3.2 as Apple doesn't offer detailed release notes, but as a minor 10.x.x update, we can expect it to focus on bug fixes and under-the-hood performance improvements rather than major new features. Apple does say the update fixes the new SiriKit car commands, which should now work as expected.
Should anything new be found in the iOS 10.3.2 beta, we'll update this post.