We, currently, remove all the old version of packages from the cooking mirror when a upgrade version is pushed. The result is that the cooking mirror does not seem to have any linux-2.6.34 packages (default linux kernel supplied with the latest cooking). I believe this was done to save the hosting space. If we have enough hosting space now, can we change "rm" to "cp" and keep the old versions too. We have kind of lost the capability to backtrack to the previous pkg version using the tazpkg. This forum post is also related to this issue : http://forum.slitaz.org/index.php/discussion/comment/9804/#Comment_9804
Other related issue is that "tazpkg upgrade" in the latest cooking seems to overwrite and remove the previous kernel completely. I used to like the old behavior where it will not remove the previous version of my kernel (maybe this interesting behavior was because of some bug that got fixed). But this is helpful in case upgrading to the new kernel has some hardware or other issues. Atleast then, I can just boot into my working copy of the kernel.