The Intrepid Ibex Alpha 2 (July 10th), is the second alpha release of Ubuntu 8.10, which, along with the very new improved features (package merge from Debian, also with brand new packages and heavy upgrading of the existing ones, Xorg - X11R7.4 with new and upgraded modules, apps/utils/drivers/libs, featuring xserver 1.5 - currently RC5 ), runs on 2.6.26-3.9 kernel, based on 2.6.26-rc8 (2.6.26-rc9 soon). The new kernel, announced on 13 Jul 2008, by Linus Torvalds, along with its stable release has many improvements from 2.6.25 (including EXT4 new - experimental - features, built-in support for remote KGDB debugging, new KVM ports and USB Video Class driver, build-in-kernel memtest, /proc/pid/mountinfo, read-only bind mounts, wireless mesh networking support, security= boot parameter, and much more stuff), along with lots of driver additions and some architecture-specific enhancements. Oh, let's not forget about the Kernel Hacking make options, where you can configure and test some of the new features.
However, there still is massively increased video drivers instability, so, while this still is an alpha release, you are advised not to install it on production machines. In the meanwhile, you can report bugs through the Ubuntu bugtracker. : )