Roll Your Own Search Engine with Zend_Search_Lucene
John Herren at Zend Developer Zone - Roll Your Own Search Engine with Zend_Search_Lucene:
"Zend_Search_Lucene is a php port of the Apache Lucene project, a full-text search engine framework. [...] In this tutorial, I'll show you how to use Zend_Search_Lucene to index and search some RSS feeds."