Hi Erich, org-exp-blocks only works with the old exporter, not the new one. It was removed from the master branch git repo in commit ee3b3eb on Mar 2. I’m not clear what version of org you are using (seems it’s not master, as the org-e-foo files have been renamed ox-foo), but you should beware of picking up an old version of some elisp files from the org-mode that comes bundled with emacs.
I’ve heard (http://thread.gmane.org/gmane.emacs.orgmode/64972/focus=65013) that the new exporter supports in some way the org-exp-blocks functionality, but I still don’t know how exactly that works. I don’t know what is causing your error specifically, but maybe making sure the lisp files you are loading all come from the same version of org will help. I *think* that you should make sure that the installation directory for org comes first in the ‘load-path’ variable then using just (require 'org) as Bastien suggests should do the trick. You might need to install the org files to a directory outside of the Emacs.app bundle, then manually add that to ‘load-path’. -- Aaron Ecay