Last month we already provided a peek into the Ubuntu 11.04 X.Org stack that covered nearly all of the same details (along with the other Ubuntu 11.04 X discussions) we are about to share, the information has been finally communicated officially by Canonical's Bryce Harrington.
Targeted for Ubuntu 11.04 is he Linux 2.6.38 kernel, X.Org Server 1.10 (or 1.9 if xorg-server 1.10 is late or risky), Mesa 7.10, the needed version of libdrm for Mesa 7.10 compatibility, and GNOME 3.0. The Intel, Radeon, and Nouveau DDX drivers will be at their latest stable versions when freezing.
As we already said, this next Ubuntu release will also use R300g (the ATI Radeon Gallium3D driver for supporting GPUs up through the Radeon X1000 series) by default rather than the classic Mesa R300 driver. The R600 driver in use will continue to be the classic alternative for Ubuntu 11.04. There will also continue to be no Nouveau Gallium3D support provided by default in Ubuntu Natty.
You can read Bryce's announcement on the mailing list. Or you can read the A Peek Into The X.Org Stack For Ubuntu 11.04, which contains greater details.
The only other note that Bryce added is that they will begin stripping the less widely-used Mesa DRI drivers from the Ubuntu CD in order to save space. Ubuntu's Jockey can be used then for installing these less popular DRI drivers for those owners of such hardware. This will be good if Canonical begins dropping Linux support for this more obscure hardware, seeing as such hardware tends to not work (or be less friendly) with the Wayland Display Server, which they intend to support by default (with a xorg-server fall-back and X application compatibility mode) in less than one year's time.