There are two times when this becomes an issue. One is on x86_64 systems where build deps can cross architectures, and the other is when using systems like openvz/virtuozzo where the glibc is often replaced or otherwise lobotomized.
Which one is yours?
Ahh, all the CentOS boxes are either x64 Xen Dom0 or U... What happens to glibc on these, especially in the Dom0 case where I hand installed the xen rpm's and glibc wasn't touched after initial update?
I assume the x86 non virt FC9 box is a coincidence.
Thanks! jlc