Thank you Eric and Erik for the incredibly quick troubleshooting. I updated .emacs with the setenv command suggested by Eric, restarted emacs and everything now works as expected.
Bryan
back when I had to use a mac, I would just symlink paths into standard
locations, e.g.
ln -s /opt/local/bin/dot /usr/bin/dot
Maybe not the most elegant solution, but it works reliably
To do this the *right* way you can update the PATH environment variable
*within* Emacs by doing something like the following
(setenv "PATH" (concat "/opt/local/bin/:" (getenv "PATH")))
Cheers -- Eric