I was having this same problem with my installation.
I have a openSUSE 10.3, glxinfo, glxgears, fglrxinfo and fgl_glxgears all seg faulted (mainly, any program that tried using OpenGL was segfaulting on me).
My problem was solved when I didn't use the built-in functionality of the installer that generates a package for the distribution, and used the installer directly.
Here's my steps (don't know how these can apply to Gentoo):
1 - Prepare kernel (taken from here):
and one last command to clean the kernel source:
# cd /usr/src/linux-<version>
# make mrproper
# make cloneconfig
# make modules_prepare
2 - Remove any previous installations:
3 - Remove any left over:
# rpm -e $(rpm -qa | grep fglrx)
4 - Run the visual setup for the ATI driver:
# rm -fR `find /lib /lib64 /usr -name *fglrx*`
Follow the steps and then reboot.
# sh <LOCATION_OF_ATI_DOWNLOAD>/ati-driver-installer-8.42.3-x86.x86_64.run
I hope it helps.