In an official Samsung video used in their press conference at the event, The Galaxy S III makes a brief appearance, and it carries visible changes from the galaxy S II.
The most noticeable difference is how thin the bezel is much thinner than the one on the S II. We have rumors confirms that the S III will have a next-gen Super AMOLED screen with a 4.6-inch diagonal, which would fit in the frame of the Galaxy S II if Samsung shaves down the bezel. We are still waiting an official Release from Samsung which is probably will be during the MWC2012
check out the video here