It will be interesting to see what the reaction to the open-source Intel drivers will be. If that's a generally positive experience, it will become much easier to see open-sourcing to other graphics companies, although I doubt Intel have anything like the software investment that ATI and nvidia have put in.
From my point of view the Intel driver is worthless as long as you have not the same chip documentation that the guys who have written it seems to have. There are too many “magic code parts†that are hard to understand. From the comments I even have the felling the developers sometimes understand it either and have written it only because it was somewhere in the chip documentation. Maybe you can fix some buffer overruns or such errors but if you want to improve the driver you are lost without the right documentation. It’s like trying to learn a language with only a newspaper in this language.