== How can we determine the version of the running kernel? ==

The official version of an Ubuntu kernel is found in the {{{/proc/version_signature}}} file.  This file contains both the full Ubuntu version of the kernel and the mainline version on which it is based.  The first field is always {{{Ubuntu}}}, the second field is the Ubuntu kernel version, and the final field is the upstream version:

    {{{
$ cat /proc/version_signature
Ubuntu 2.6.35-6.9-generic 2.6.35-rc3
$
}}}