Unfortunately, I do not remember the links, but one was the german Wikipedia entry for "Xgl", and another one was a german Xgl user group WIKI, and I also remember an interview with a Trolltech QT developer, who also was mentioning something like this.
If it is what you are referring to, this would be a little bit of a disappointment for me, since I already know these beta drivers, and they are not what I was looking for. I was referring to a driver that would work like the Mesa-fbdev resp. Mesa-Solo OpenGL implementation, which provides hardware acceleratet (through DRI) OpenGL without having to install the X-Window system.
The Xegl project uses this to implement the EGL API and on top of it a Xgl-like X-Server, so in the future you won't have to have Xgl running inside another X-Server. What is best and unique to the Xegl solution is that it seperates the concerns of the Windowing system from the hardware driver aspects cleanly, and thus is an architectural superior approch above integrating hardware drivers into the windowing system, as it is done now.
I just was thinking that NVIDIA already has released drivers for that, but if your statement is true, this doesn't seem to be the case...
For a more comprehensive discussion about this topic, see this
thread (quite old, but still an open issue).