Intel has a whole site to supporting their graphics in Linux: http://www.intellinuxgraphics.org
They also have a huge set of documents available to help the Linux driver developer: http://www.intellinuxgraphics.org/documentation.html
They are support by X.org, Mesa, Linux Kernel, Linux DRM, and BSD DRM. They don't have any funky licensing, but relay on the MIT and GPL licensing: http://www.intellinuxgraphics.org/license.html
I am very impressed.
