This is strange because I was able to get the error below to go away by removing the reference to libm.
gcc -o example example.o -Wl -L/home/kensey/cdev/lib
Just to add to the list of answers, http://fedoraproject.org/wiki/UnderstandingDSOLinkChange It is informative. It isn't relevant to the question asked above, but, the explanation relates to the error message /usr/bin/ld: note: 'some_reference' is defined in DSO some.so so try adding it to the linker command line