We have already reported on the X.Org and Mesa plans for Ubuntu 10.10 along with what major packages are looking to be included along with the work towards a rootless X.Org Server and how it may be easier to run a Wayland Display Server. The game-plan for Ubuntu 10.10 is to ship with X.Org Server 1.9, but until that is ready, X.Org Server 1.8 is being used.
Ubuntu 10.04 LTS is using X.Org Server 1.7.6, which is what's being used right now within Ubuntu 10.10 Alpha 1 and the current Maverick packages, but X.Org Server 1.8 from Debian is being pulled in the coming days. Once X.Org Server 1.9.0 has been released or a sane development snapshot with assurance it will be officially released in time for the October release of Ubuntu 10.10, X.Org Server 1.9 will then replace the 1.8.x release.
The current plans put the release of X.Org Server 1.9 as coming in August and all indications are that this release schedule shall be met. In this move from the 1.7 to 1.8 series, the ABI is broken for the input and video drivers, which requires that these X.Org drivers be rebuilt otherwise they will not function. This may cause some pain for those habitually tracking the Maverick development packages on a daily basis, but the process should go rather smoothly.
Once rebuilt the new open-source graphics and input drivers should work just fine (and in some cases better against the newer X.Org Server). The proprietary NVIDIA driver is also compatible with X.Org Server 1.8, but to no surprise, the ATI Catalyst Linux driver from AMD is not yet compatible. This means that those tracking Ubuntu 10.10 "Maverick Meerkat" right now will be forced to use the open-source ATI graphics stack as the fglrx/Catalyst driver will not work. At some point before October, however, AMD should introduce the needed support and we just need to hope they'll be quick with their adjoining X.Org Server 1.9 support that is entering Maverick later in the cycle.
Confirmation of X.Org Server 1.8 soon being pulled into Ubuntu 10.10 repositories can be found on the Ubuntu-X mailing list.