This October Intel will be providing a driver update for Ivy Bridge that will enable 4K x 2K resolution support as well as hardware accelerated 4K video decode. You'll need to use two DP outputs to drive a 4K panel from an Ivy Bridge system, which unfortunately makes it so most existing Ivy Bridge systems won't be able to drive the higher resolution panels. 

Haswell will support driving a 4K display off of a single DP output or HDMI.