A state tracker is an implementation term for the Gallium architecture. To the outside world Gallium is just a driver that has different flavours expressed by the state tracker. Or put another way, the gallium bottom half + the state tracker is a XXX driver. So under windows, you have a common bottom half and a top half that varies from driver flavor to flavor.
The end result is that instead of having a full D3D9, D3D10, D3D11, OpenCL and OpenGL driver, you have a single Gallium bottom half, as well considerably smaller top layers.
Although I don't know for sure, I would expect that the model that they are taking is having a Gallium bottom half that allows vmware to jump out to the host system. Then VMWare will just be a GL accelerated client on the host that will allow close to full speed HW acceleration for all the GPU clients within any number of guests.
If someone wants to have an open source dx tracker he could build it ... and it's not said, that vmware won't opensource this driver after a while ... when the commercial benefit of closed source is gone they have no need or interst to keep it closed.
I am quite sure they have an NDA with MS. Wouldn't have happened so quickly otherwise I guess. So that would mean, commercial use or not there'd still be an NDA.
Still sad I would have hoped that this could've been used by wine excessively so wine would just need to "correct" the behaviour of w32 progs in terms of everything else. Which would cost probably far less performance that the DX->OpenGl transaltions.
But then I'm not a developer and know little about all that.