It would be great to keep versions of the linux kernel sources that are used for any of the latest live cds until those cds are superseded by a more recent version. This would allow people to emerge exactly the sources used for those live cds to build some additional modules or the like. Concrete example: install-x86-minimal-2005.0.iso uses 2.6.11-gentoo-r3, but portage only contains nothing between gentoo-sources-2.6.10-r7.ebuild and gentoo-sources-2.6.11-r8.ebuild.
This has nothing to do with the livecd herd.
The main reason we remove ebuilds is because older kernels have security problems. We don't support ebuilds older than stable either. Also, in your example, there is very little difference between 2.6.11-r3 and 2.6.11-r8, so its a bit of a non-issue. If you really want to, you can pull the old ebuilds out of viewcvs.gentoo.org.
