The Xbox One doesn't come packaged with a headset. Nor can you use your existing, likely expensive headset, apparently. At least not until Microsoft comes up with a fix.
"The Wireless Controller has been redesigned to allow for higher data transfer speed between the controller and the console," a Microsoft representative told GameInformer. "This also required creating a new expansion port design for headsets and future controller add-on devices which is different from a standard audio plug input. Xbox plans to develop solutions in the near future to allow consumers to connect many brands of wired gaming headsets to the Wireless Controller for gaming and chat audio.”
"Near future" doesn't exactly sound like "at launch." I guess if you want a headset at launch you can shell out for a Xbox One specific Turtle Beach or the inevitable Microsoft proprietary headset.