First, in a somewhat counter-intuitive move that is drawing some criticism, there will no longer be complete Blu-ray 3D/Blu-ray/DVD/Digital Copy packages - you either have to choose between a 3D-only Blu-ray or 2D-only Blu-ray/DVD package. Also, Disney is replacing its traditional iTunes-based Digital Copy Disc format (referred to as Disney Digital Copy), previously provided with its Blu-ray/DVD Disc packages, with its new Digital Copy Plus system.
The new system replaces the standard Digital Copy Disc with a code number that allows purchasers access to a Digital Copy via the Cloud from several different services that include iTunes, Amazon Instant Video, and Vudu. What is interesting is that although Digital Copy Plus expands access, it is not the same as the Ultraviolet Digital Copy system used by several other studios, including Lionsgate, Paramount, and Universal.
For more details on how the system works, including important information on digital copy code expiration dates, check out the Disney Digital Copy Plus Redemption and Help (may not be full time up until the official June 11, 2013 Blu-ray Disc release date of Oz The Great and Powerful).