updated 04:42 pm EDT, Fri May 16, 2014
Dell, Panasonic monitors added to compatibility list
Following the release of OS X 10.9.3,, Apple has updated a document on using 4K displays with 2013 models of the Mac Pro and 15-inch Retina MacBook Pro. Apple mentions that several new monitors are supported, including the Panasonic TC-L65WT600, and Dell's UP2414Q and UP3214Q. Prior to v10.9.3, only the Sharp PN-K321 and ASUS PQ321Q were officially compatible.
A new section in the document discusses display adjustments and v10.9.3's new Retina scaling, which makes OS X more legible at 4K. Also mentioned is support for 60Hz 4K output using multistream transport; to take advantage of this, though, a monitor must be set to enable MST, which may in turn require updating its firmware.