A month ago the Canonical crew working on Ubuntu 10.04 LTS received an unreleased Catalyst 10.4 driver
from AMD for inclusion with the Lucid Lynx since the publicly available ATI Catalyst drivers had not -- and to this day still do not -- support the X.Org Server 1.7 used by this next Ubuntu release. Similar pre-releases for Ubuntu have happened in the past
when AMD hasn't been quick to the game in supporting new Linux kernels and X Servers. This driver was made available in Ubuntu 10.04 even before Catalyst 10.3
was released. Catalyst 10.4 still has not been publicly released, but another updated 10.4 driver has made its way into the Lucid repository.
As a Sunday morning update, an updated fglrx-installer package has entered Lucid that provides a new upstream release. As is shared by this mailing list message
, fglrx 8.723.1 fixes an issue with the X.Org Server causing a segmentation fault when certain ATI graphics cards are installed. There may be other changes too "under the hood" with this driver release, but that's all that is officially mentioned.
The ATI Catalyst 10.4 for the rest of the Linux world (and Windows users too) should come later this month. The official release of Ubuntu 10.04 LTS is expected on the 29th of April.