Where is the changelog for Ubuntu kernels?

The latest version of the kernel for Ubuntu can be seen on Launchpad. See all current changelogs here:

• http://changelogs.ubuntu.com/changelogs/pool/main/l/linux/
• https://launchpad.net/ubuntu/+source/linux/+changelog

That should tell you what changed in each release.

Given that your main aim is to build your own kernel packages though, you might be better off following these guides:

• https://wiki.ubuntu.com/KernelTeam/GitKernelBuild
• https://help.ubuntu.com/community/Kernel/Compile

You could also add the relevant repos for lucid (it will not harm your system, given that the packages have older version number, so are ignored in dist-upgrade), update the cache and use the command

apt-get changelog linux-image-$version

I find http://kernelnewbies.org/LinuxChanges to be more human readable for each Major Kernel change (2.6.31, 2.6.32... 2.6.39)

For individual kernel versions i normally go here:

http://kernelnewbies.org/Linux26Changes

Which shows in a more human readable way what is new, improved or fixed in each kernel version release.

NOTE: Not related to specific Ubuntu kernel releases but as help for kernel news for future Ubuntu versions.