Alan Cox has posted a set of 12 patches for the GMA500 Linux KMS/DRM driver. This driver provides KMS support for the Poulsbo/Oaktrail/Cedarview/Medfield graphics processors, but the Medfield support is being left out of this initial merge since the support isn't fully ready at the moment.
There's also no hardware acceleration support in the GMA500 DRM driver, but it at least has kernel mode-setting in shape and is ready to exit staging. (Except there is 2D acceleraton for some devices. It's also possible that video overlay support for Poulsbo could be written based upon publicly available information, says Alan Cox, but that's a big effort.) This GMA500 Linux driver does use GEM (the Graphics Execution Manager) plus some of its own glue for memory managing.
While Poulsbo hardware is quite well known to Linux users due to its notorious support being derived from PowerVR SGX graphics, the Oaktrail (GMA600) is found in many tablet/slate PCs, along with Cedarview.
These patches to move this open-source Intel Linux driver out of staging can be found here. With the Linux 3.2 kernel merge window still being open, it's possible that it will be merged in the next week for this next kernel release.