A comprehensive and up-to-date list of the new features has been posted on the Ubuntu Forums.
Development of Ubuntu 8.10 started with the Linux 2.6.26 kernel, compared to version 2.6.24 in Ubuntu 8.04. Just recently, it was decided to use the 2.6.27 kernel instead. The main reason for the switch is to avoid having to update the older kernel with things already in 2.6.27.
This is unusual for an Ubuntu release, typically the kernel has been upgraded two versions. The last time the kernel was upgraded three versions in an Ubuntu release was Ubuntu 7.04 (Edgy’s 2.6.17 to Feisty’s 2.6.20).
The last number in the kernel version being odd indicates a kernel with larger changes than an even numbered kernel. However, both even and odd kernels are considered stable.
The new Linux kernel needs to be tested! An up-to-date installation of Ubuntu 8.10 should now include it.