Here is a updated version of the patch to add support for extended attributes on MacOS X and Linux. It is the same code and functionality as what is in the xattr branch in git, just updated to apply cleanly against the master branch as of 2010-02-21. I've been using this under Fedora 12 client-only (for tripwire: without a radmind server) for three weeks and I have not discovered any problems.
xattr patch against current master (23ebbda)
Assigning Andrew so he will notice it.