Ultra HD / 4K displays will increase in sales in 2014 and so Intel's Damien Lespiau has queued up improvements for X.Org Server 1.16 in handling the higher resolution modes.
The change made to the X.Org Server is about not pruning 4K modes when using HDMI 4K monitors. The X.Org Server DDC code now needs to read the max TMDS frequency field in the HDMI CEA vendor data block to check the mode dot clock. This change has already been tested by Intel QA and is in use by ChromeOS already for 4K HDMI support.
There's currently a Git pull request for the ~150 lines of code to support HDMI 4K via the X.Org Server. The next X.Org Server release is due for release in July.
Back in November I shared my early results on Ultra HD 4K Linux graphics card testing while additional 4K Linux tests are forthcoming on Phoronix with the latest Linux graphics drivers and hardware