I have searched high and low for answer to this issue. I am using boost 1.48 and the program is extremely simple, since I have broken it down to its simplest form in order
Put the source file at the beginning of the command line.
Try
g++ -m32 -Wall mapnik-test.cpp -o mapnik-test -L/usr/lib -I/usr/include -I/usr/include/freetype2 -lpthread -lboost_system
The libraries should be specified only after the source file so that the linker can resolve the undefined references in the source file.