"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AT&T's iPhone 3G Data Plan and No Longer Revenue Sharing
The new iPhones will cost $199 (8GB) and $299 (16GB) with an unlimited 3G data plan costing $30/month. This is an increase from the current $20/month unlimited EDGE data plan for the 1st generation iPhone. Voice plans continue to start at $39.99, but no additional details are provided.
Meanwhile, AT&T reveals that Apple will no longer receive the revenue sharing from each users plans. It was highly publicized that AT&T paid Apple a portion of its monthly recurring service charges for each iPhone user. Under the new agreement, there is no revenue sharing. AT&T is presumably directing that money towards the $200 subsidy for the iPhone.
Update: Arstechnica was able to speak to an AT&T representative who claims that if existing iPhone owners buy an iPhone 3G, the new 2 year contract replaces the current contract rather than extending it.