As I’ve already written in the ubuntu-devel mailing list, a new fglrx driver (2:8.840-0ubuntu1) is now available in Natty and it finally works with the new xserver. There are still a few issues whose fixes should land after Beta 1 is released:

1) compiz needs to be updated so that fglrx can work with Unity. Currently the “Classic Desktop” session works well but the “Ubuntu Desktop” one doesn’t. If you’d like to test Unity with the new driver, you can use Unity’s daily builds from the PPA, as described here.

2) currently the driver is not offered for installation in Jockey. A fix is already available in Jockey’s development branch though. In the meantime, if you wish to install the new fglrx driver, you can do it manually by following these commands:

sudo apt-get install fglrx
sudo update-alternatives --config gl_conf (and select the line with fglrx)
sudo update-initramfs -u

and finally reboot. No xorg.conf is required as the driver will be automatically loaded.

Note: despite what the relevant article from Phoronix claims, the driver doesn’t support AMD’s PowerXpress.