The main feature of the Intel DRM in the Linux 2.6.35 kernel was H.264 VA-API decoding support with Intel's newest graphics processors. The Linux 2.6.36 kernel should bring in greater eDP support, various patches all over, and tracepoints support for page-flipping and vblank support. Intel's Embedded DisplayPort (eDP) support within their KMS driver has been ongoing for better supporting this interface that's used internally on newer notebooks for their display panels.
The ATI Radeon DRM driver changes are most prominent and include R600/700 tiling support, R300/500 Hyper-Z support, support for reading thermal sensors on most R600 ASICs, R600 kernel bit state emission minimization, ioport accessors for BIOS scripts, under-scan support for HDMI TVs, and RS690 HDMI audio support. For those unfamiliar with Hyper-Z, it is an ATI technology that originates with their R100 chipsets and is designed to improve rendering efficiency by providing Z-buffer compression, fast clear support of a Z-buffer, and hierarchical Z-buffer that throws out useless pixels before hitting the rendering pipeline.
With the Nouveau DRM for providing open-source graphics support on Linux for NVIDIA graphics processors, the 2.6.36 DRM will offer improved suspend-and-resume support for the NV10 through NV40 GPUs, SIL164 i2C chip support, improved NV50 DisplayPort along with hot-plug support, and EDID over ACPI support.
The core Linux DRM code has BKL removal, whitespace clean-ups, non-PCI DRM layer support, memory leak fixes, and support for vblank tracepoints.
David's pull request announcing these major changes (plus lots of other minor work) for the Linux 2.6.36 kernel can be read on dri-devel.