Because I had no idea what it was:

    Gallium3D is a software library for 3D graphics device drivers being
    developed by VMware, after they acquired Tungsten Graphics[1]—the original
    authors.
    
    The Gallium3D library operates as a layer between the graphics API and the
    operating system with the primary goal of making driver development easier,
    bundling otherwise duplicated code of several different drivers at a single
    point (this is done by providing a better division of labor, for example,
    leaving memory management to the kernel DRI driver) and to support modern
    hardware architectures.
    
    Gallium3D is currently used by the free and open source nouveau graphics
    driver.

http://en.wikipedia.org/wiki/Gallium3D

Death to dual booting. I can't wait for this and spice[1] to mature, having to be tethered to a powerful machine for any use case is frustrating when so much else is accessible remotely with ease.

Also it's always nice to see corporate contributions of big features to open source graphics:

> Thanks to all the Gallium contributors and especially the VMware team, whose work made it possible to implement Direct3D 10/11 much more easily than it would have been otherwise.

[1] http://spice-space.org/features.html

Some context:

http://lists.freedesktop.org/archives/mesa-dev/2010-Septembe...

Is this a cleanroom implementation?

Also, I'm certain MS holds some form of IP on the DirectX line of products. Have they made any threatening noises?

It would be pretty ironic if this enables D3D 10 on Windows XP.

That would only be possible if the framework of Gallium3D can be ported to use the Windows DDK. Gallium is pretty well tied to X11 and a few kernel features present on BSD and Linux kernels.