I thought about that and I already had nvidia-cg-toolkit installed but the libs were 64-bit and that package doesn't seem to provide a multilib solution. There is a bug on the Gentoo bug tracker for that issue: http://bugs.gentoo.org/show_bug.cgi?id=262477
I went ahead and pulled down the 32-bit version of the package that matched the version installed by portage and I dropped the precompiled libs into the lib directory in the BlackPlague folder. That resulted in:
./blackplague.bin: /opt/PenumbraCollection/BlackPlague/lib/libCgGL.so: no version information available (required by ./blackplague.bin)
./blackplague.bin: /opt/PenumbraCollection/BlackPlague/lib/libCg.so: no version information available (required by ./blackplague.bin)
The issue remains unchanged. Thanks for your assistance so far.