"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AT&T Moves Up iPhone Upgrade Eligibility On Eve of WWDC Keynote
On the eve of the WWDC 2010 keynote and what is believed to be the announcement of the next generation iPhone, AT&T seems to have adjusted user eligibility requirements forward for many customers. This means that several readers who previously were ineligible to purchase a new subsidized iPhone now find that they are eligible. Previously, dates for eligibility ranged from June to November depending on your rate plan.
Current AT&T customers can check at http://wireless.att.com by clicking on "Check Upgrade Options" after they log in. The improved eligibility requirements will allow existing customers to upgrade to the new iPhone with no early termination fees. Apple is widely expected to introduce the new iPhone at the WWDC 2010 Keynote on Monday, June 7th. The keynote begins at 10 a.m. Pacific.