No physical buttons. There was apparently mention in the press conference of being able to re-zone the default page-turning areas, but no User's Guide is available yet.
From the product page:
"Amazon invented a new type of touch experience that eliminates the fatigue caused by continuously swiping to turn the page, and that allows readers to hold Kindle with either hand while still turning pages comfortably. With EasyReach, Kindle Touch users can effortlessly page forward in a book or a periodical while holding the device with either hand. Tapping on most of the screen area will page forward, the most common action done when reading; tapping in a narrow area near the left edge of the device turns to the previous page; and tapping on the top part of the screen brings up the toolbars for further options."