While Intel won't even be releasing their next-generation Haswell processors until H1'2013, for months already they have been putting out the open-source Linux code to get the new product support ready. Back in March is when Intel began releasing Haswell graphics driver code for Linux. They've already made a few code drops and have begun integrating this new code with the mainline Linux code-bases.
On Thursday there were 21 new Haswell patches released by Eugeni Dodonov of Intel's Open-Source Technology Center. These latest patches provide support for DisplayPort and Embedded DisplayPort (eDP) to accompany the existing HDMI and DVI outputs. Aside from expanding the Haswell connector support, these latest patches also enable RC6 power-savings support for Haswell.
There's still other Haswell Intel Linux DRM kernel driver patches to be released but Dodonov writes in his mailing list message that the kernel driver is already approaching parity with the level of Linux kernel support for the current-generation Ivy Bridge platform.
So in overall, with those patches, the status of Haswell support should be more or less on-par with Ivy Bridge kernel-wise. Most things that were working on IVB should be available on HSW - and if they don't work it is probably a bug, so please let me know about it.Of course, in the months ahead Intel OTC developers still have a lot of work to do when it comes to optimizing performance, catching up with OpenGL support, maybe providing some level of OpenCL support, etc.
Outside of the graphics found on the Haswell die, Intel Linux engineers have also been working on enabling other areas of the chip, providing compiler support for new CPU extensions, and making other continued open-source enhancements for Linux. Intel has also been busy at enabling the Valley View Atom under Linux and last but not least has been putting out open-source code for Knights Corner.