An official announcement was planed for May 1st, but might be sooner now that the info has been leaked. The story is set in the future, but uses current generation weapons and the loading screens are now dynamic. Instead of a 5 second count-down timer, players will repel off a helicopter to drop into the map.
Players will be able to peak around corners, slide while shooting and roll when prone.
Also revealed is that MW4 will be next gen only, so PS4 and Xbox720 or whatever they plan on calling it and of course PCs.