During my visit to Wizards' offices two months ago, Mike Turian (Pro Tour Hall of Famer, R&D member and now member of Organized Play) told me about something "big" he was working on, an idea which predicated his transition from R&D to Organized Play. I can only guess that the announced "Magic Celebration" is this event.
Details for it are scarce except that it will be run through the WPN and it will take place on Sept. 10th, 2011. It is being announced as part of the info packet distributed with Duels of the Planeswalkers 2012 promotional material, but the details are scarce, our packet said only the following:
An event unlike any other we’ve run before, Magic Celebration will bring together Duels of the Planeswalkers and Magic 2012 Core Set players on September 10th at WPN locations around the globe. More details will be unveiled as we get closer to the event, but you can learn more about Magic’s in-store events and find a hobby store near you at Wizards.com/locator.