The latest release of PEAR::OAI has just been announced [1].
PEAR::OAI is a PHP class library for the Open Archives Initiative Protocol for Metadata Harvesting [2]. This library provides a Server (= Repository) and in the future also a Client (= Harvester) interface. This package is conformant to and makes use of PEAR [3] classes.
[1] http://sourceforge.net/forum/forum.php?forum_id=288894
[2] http://www.openarchives.org
[3] http://pear.php.net