Chris,
Well the first thing to try woud be adding a "-lcrypto" to the MODLIBS line, but that error message almost looks like there's a problem in how libpq was built (it looks like it's complaining about not having a direct reference to the BIO_free symbol, which would have been set when libpq.a was built).
Do you actually need SSL inside your database? The quick and dirty solution is to rebuild PG without SSL, since that seems to be the source of these problems...
Another thing to try would be to rename all the libpq.so.whatever files under /usr/local/pgsql/lib to libpq.dylib.whatever and rebuild nspostgres - that might let nspostgres link to the shared rather than static version of libpq, which might fix the problem with indirect references. In which case the problem is with the postgres build scripts for using the wrong extension for shared libraries on OSX...
