"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
Steve Jobs and Apple Executives to Keynote WWDC (Officially)
This year's WWDC will be showcasing both Mac OS X and OS X iPhone:
The five-day WWDC event, which runs from June 9 to June 13, will feature the first ever iPhone track for mobile developers with in-depth sessions and hands-on labs to fully explore the capabilities of the OS X iPhone 2.0 software, including the iPhone SDK and the App Store, a breakthrough way for developers to wirelessly deliver their applications to iPhone and iPod touch users.
Apple is widely expected to introduce a 3G-capable iPhone at this year's WWDC.