During Microsoft's pre-E3 Xbox One event, EA revealed an Xbox One exclusive: Battlefield 4: Second Assault. It's a map pack that will launch on Xbox One before anywhere else.
Update: The trailer from EA's part of the Xbox E3 keynote has been added to the post above.
Update 2: An EA representative indicates that Second Assault will be a collection of four "fan-favorite" maps in Battlefield 4. The Second Assault map pack will be available sometime after the launch of Battlefield 4 on October 29, first on Xbox One.