I've got some bad news, guys. Amazon has stopped selling discs of forthcoming Disney movies, including Muppets Most Wanted (August 12), Captain America: The Winter Soldier (September 9), Million Dollar Arm (October 7) and Maleficent (November 4).
Read these sources for more information:
Disney Disc Preorders Disappear from Amazon | Home Media Magazine
Amazon Takes the Muppets Off the Shelf | NYTimes.com
Amazon in Sales Dispute with Disney Over Upcoming DVD Releases | The Disney Blog