Smells like you're using libstdc++ instead of liblstdc++ to link your final executable. This fun problem only manifests itself on 5.x, and is documented in the README.FreeBSD file in devel/linuxthread's work directory.
This document is pointed to in passing by the port after it finishes installing, but is easy to miss, and is not accessible unless you neglect to clean your port after installing.
See my thread at
http://www.everquestserver.com/forum...ic.php?t=12004
for patches against 0.5.3dr2 that allow for use of Perl and shared memory on FreeBSD 5.x with gcc 3.3.