Linux kernel 2.6.27, in development at RC8, has been prepared for Intrepid. This is from 2.6.26-5.15, Ubuntu's modified version of Linux kernel 2.6.26.
This is a good move, since by Intrepid's KernelFreeze on October 16th, this version will have matured. Also, the Ubuntu developers noticed, that this version focused unusually on bug-fixes and also introduced dependencies necessary for 8.10 pre-configured (such as ALSA 1.0.17 needed for PulseAudio 0.9.11, which fixes a lot of regressions that many Ubuntu-ers are facing.)
At Hardy's release, it shipped a one late version of the Linux kernel, due to Ubuntu's motto "Always stick to an old version, no matter what." Just kidding; it's just that Ubuntu always does this to its default applications (*cough-Transmission-cough*) due to its early feature freezes. It's very possible that 2.6.27 will reach final release by 8.10 final, but even if it doesn't, it will be stable, no doubt.
Other than that, this, like with all kernel updates, supports new hardware and improves compatibility with existing hardware. Nice.
So after much discussion, decisions were made to move to 2.6.27, which will hopefully provide "a more robust experience" for users.
UPDATE: I've learned from this Tombuntu article some information about kernels:
- Odd number releases are less stable than even number releases because they introduce more features, but nevertheless still stable.
- The last time Ubuntu updated a kernel 3 versions was from Edgy to Feisty, which is unusual, as it usually updates two versions.
UPDATE 2: Added last three intrepid-changes links.