These RXTX files were just copied directly from the 0103 released of 
Processing.  

Their versions are reported as:
 Native lib Version = RXTX-2.1-7pre17
 Java lib Version   = RXTX-2.1-7pre17




If you've never used RXTX before on your Mac OS X box, run the command:

% ./macosx_setup.command

And then shutdown (not just log out) and log back in again.
And read this faq from Processing: http://processing.org/faq/bugs.html#serial