Extracting the tarball of glibc might not be sufficient if you have the other (the broken one) still on your filesystem cause portage thinks you're still using it. It would be a good idea to extract the tarball to have a working system and then reextracting it but trough portage (i think it is emerge -k glibc if i remember but check man emerge cause i'm not sure). I think the source of this problem is that env-update (which is invoked after every package merging) create symlinks pointing to your broken glibc.
Nicolas -- gentoo-ppc-user@gentoo.org mailing list