otool -L /Library/PostgreSQL/8.4/pgAdmin3.app/Contents/MacOS/pgAdmin3 | grep libpq
@executable_path/../../Contents/Frameworks/libpq.5.dylib (compatibility version 5.0.0, current version 5.2.0)
@executable_path/../../Contents/Frameworks/libpq.5.dylib (compatibility version 5.0.0, current version 5.2.0)
{This tells me that version 8.4 uses libpq.5.dylib}
{The symlink shown below allowed me to use the libpq.dylib from "pgAdmin3"}
1. cd /Library/PostgreSQL/8.4/pgAdmin3.app/Contents/MacOS/Frameworks
2. sudo ln -s libpq.5.dylib /usr/lib/libpq.dylib