In September of 2010 there was the introduction of the Gallium3D d3d1x state tracker that implemented the Direct3D 10/11 API for use on this open-source graphics driver architecture. Besides still being present in the mainline Mesa tree, it's still worked on from time-to-time, but unfortunately really isn't used.
Wine developers had mixed feelings over this state tracker when it was introduced with concerns over possible legal problems and the state tracker being limited to Gallium3D drivers (so just the Radeon/Nouveau on Linux and not really any driver support for other platforms or hardware), among other issues. Nothing has changed in terms of Wine possibly hooking into this state tracker while their Direct3D 10/11 support in Wine is still very limited. There hasn't been any other adoption breakthroughs either for this state tracker.
As can be seen from the d3d1x commit log, this state tracker is still actively maintained with the last commit being from just four days ago.
That commit from last week touched around 250 lines of code as it implemented the new stream output interface for Gallium3D. The other commits to this state tracker for Microsoft's graphics API bring a variety of fixes, new support features, and other work. Most of the d3d1x state tracker work is handled by Christoph Bumiller. In total for 2011 there was around 50 commits to this driver component.
Those wanting to dive into the source for d3d1x can find it from the web viewer.