Jeremy,NH6Z, has an Xastir-2.0.x package available for OSX at:
http://www.nh6z.net/sites/default/files/Xastir.zip
THESE ARE THE CAVEATS TO THIS INSTALL. IF YOU SCREW UP YOUR INSTALL BY NOT READING THESE, I'LL NOT BE RESPONSIBLE (not that I'm responsible anyhow):
1) THE MAPS ARE IN THE APPLICATION BUNDLE SO BACK THEM UP. If you forget to do so, and drop the new binary on the old one, you'll blow away all your maps and have to reacquire and reinstall them.
2) AS ALWAYS, ONLY EXECUTE THIS FROM THE /Applications DIRECTORY. Otherwise it has the potential of screwing up your .xastir directory. You don't want that.
Dana, N1OFZ, has compiled xastir for Mac OS X and assembled a package for easy installation. You can find it at Dana's site:
Note: The below is not currently available from Dana's page.