Speaking about Ubuntu packaged kernels only...
Everything that goes into the source package is in git. Every release has a signed tag. Ubuntu kernel package names have a strict naming convention that makes upgrading and abi checking work right, so from my perspective putting the tag name somewhere in the binary package is much more realistic than forcing a new naming convention on the package name. Kernel image packages have the config used to generate them in /boot we could easily add another file that contained the git tag. We could also put a git log from a known upstream Linus or stable release in there but that log could be long. It would have all the linaro patches plus all the Ubuntu patches.
john