Description of problem: The glibc-common 2.8-8 package has glibc-common 2.8-3 as a dependency, however on PPC the package is glib-common-2.8-3.ppc. Version-Release number of selected component (if applicable): How reproducible: Try to update using yum/any gui. I was able to work around it by manually downloading the glibc-common-2.8-8 package and --force installing it with rpm.
glibc* 2.8-8 of course has no dependency on 2.8-3. Must have been a problem either on your side, or running against incomplete mirror and having both ppc and ppc64 glibcs installed and only one of them getting updated. Anyway, there are no bugs in the glibc* dependencies and they haven't changed for years.