Last August was when Samsung published the Exynos DRM driver that was merged into the mainline Linux kernel (Linux 3.2 kernel) and the first ARM SoC graphics driver to hit the Direct Rendering Manager sub-system, which was then followed by the Texas Instruments OMAP DRM driver.
Since it went mainline, Samsung has kept working on the Exynos DRM driver with adding new features and improvements during each kernel's merge window. For this current cycle, the Linux 3.4 kernel, Samsung made some very exciting improvements.
The Exynos driver for the Linux 3.4 kernel has HDMI 1.4 support, a new buffer allocation type, a new DMA address interface for GEM/2D acceleration handling, and a virtual display driver. There was also originally a Samsung "G2D driver" for this merge window as a means of direct-rendering 2D graphics acceleration, but that's been delayed due to the Linux 3.5 kernel to allow it more time to bake.
What's new in Samsung's open-source land now is Exynos libdrm support. Inki Dae of Samsung published the 560+ line patch to the mailing list this morning. "This patch adds libdrm_exynos helper layer that inclues some intefaces for exynos specific gem and virtual display driver and also adds exynos module name to modtest and vbltest."
At the moment there isn't a "xf86-video-exynos" X.Org driver to take advantage of the libdrm support, but hopefully it will be worked on. At least though the xf86-video-modesetting driver can work in a generic way atop the Exynos DRM side. There's also not yet any Mesa/Gallium3D driver for Exynos, but that's a much greater dream and would first require significantly more DRM work.
Last week there were also some libdrm changes, including patches for Texas Instruments OMAP support for this user-space DRM library.