After reading some of the comments in a few recent posts, I just wanted to say, that the ATI Opensource graphics driver is working great for me. I use LinuxfromScratch as my main distribution, where all the software is compiled from sourcecode.
Originally the proud owner of a Radeon 9200 almost a decade ago, and I was happy with how it was working. As time went on, Intel came out with their X3000 and open drivers and it worked great. (Later on, I found out that I messed up, and did even better with Direct Rendering, and modesetting support was also a nice later addition). Stuck through with the 965G even through the GEM turmoil. It was around this time that the radeon driver started looking quite good, and my next motherboard was a 890GX (ATI 4200 inside?), and finally to my current XFX 6870 (noisy fan though, but windows handles the fan the same way).
I wanted a driver that is opensource, and supported upstream with freedesktop.org and the kernel. I want it to continue working even with the latest kernels, and the latest xorg, without jumping through extra hoops. I also want it to work with the standard xorg extensions such as xrandr, and to run side by side w/ other drivers. xf86-video-radeon does that.
I do as much work in X, as I do out of X. the framebuffer drivers are quite nice to work with.
Looking forward to the opencl support as well as OpenGL 3.0. Always love tinkering with the new technologies.
I rarely install closedsource software on my own linux machine, preferring opensource where possible. Saying that, I do not like the way the ATI/Nvidia closed driver integrates into a system. It replaces a few of the xorg libraries (libglx if I recall) that have to be restored if I want to get rid of the driver. By replacing those libraries, it makes the system only usable for whatever that one driver supports. (ex:/ install ati closedsource driver, the nvidia cards will not be working well). Also, I usually run with the latest upstream Xserver, and kernel. The closedsource drivers force me to reinstall after such an update, if they even support the latest Xserver and kernel. Also, the last time I explored the drivers, they brought back /etc/X11/xorg.conf
On the other hand, the noveau project, is a unknown for me. I have never had a reason to move away from ati. It sounds like they have done an amazing job w/o nvidia's help.