As mentioned on the Zend Developer Zone, there's a new post on kapustabrothers.com about a method for indexing all of those PDF files your site uses with the help of the Zend Framework's Zend_Search_Lucene component.

along with many others have been trying and asking how to index and search PDF files. Once Zend released its Framework, which is a port of Java Lucene to PHP, I decided to jump on board and find a way to index and search PDF files.

He uses the XPDF software to parse out the PDF files and the ZF component to do the actual indexing and searching. XPDF extracts key information from the PDF and puts it out to a new file where Zend_Search_Lucene can get to it. Example code is included to show the automatic creation of these details and how to add them to the component's index.