Thomas Hellström, the same TG employee working on the VIA 3D code, has announced that his branch of the OpenChrome driver now implements the TTM (Translation Table Maps) memory manager. TTM was set to become the de facto standard for in-kernel GPU memory management until Intel had conceived the Graphics Execution Manager (a.k.a. GEM). This open-source VIA driver using the TTM memory manager will run, but XvMC and EXA (when using the latest X Server 1.6 bits) acceleration are both lacking.
Using this driver requires checking out the branch of DRM and libdrm that provides the new TTM management support. For more information on what's needed if you want to check out this TTM-based driver, follow this thread on the OpenChrome mailing list. Unlike the open-source ATI and NVIDIA driver implementations that are using a GEM-ified TTM manager whereby TTM is used internally to manage the memory but externally it implements the GEM API, this isn't the case with VIA. However, Tungsten Graphics is the company that developed TTM, which is why they may be a bit hesitant to play with GEM.