Dan Scott has an announcement today about the official release of his File_MARC PEAR package, version 0.1.0 alpha.
What does this mean? Well, assuming you have PHP 5.1+ and PEAR installed, you can now download and install File_MARC and its prerequisite with a simple command. I've also imported the File_MARC source into the PEAR CVS repository, so you can poke and prod and provide patches.
He notes some of the changes he wants to make before things hit version 1.0, including MARCXML support.