David Cummins has a neat little post up about replicating some of Solr’s features in a PHP based solution. His post “Fulltext search as a webservice” should sound familiar to Solr’s approach from the title, and David describes how they built a similiar solution on top of Zend_Search_Lucene (Solr also uses Lucene in the backend). Seems like it would be easier to just set up a dedicated Solr cluster instead, but hey, how often has “it would be easier to do something else” sparked innovation?
I’d also like to note that the coming Solr 1.3 supports php serialization as an output format, so you can just unserialize() the response from Solr. Should provide for even easier integration between PHP and Solr in the future. While on the subject, I’d like to suggest reading Stemming in Zend_Search_Lucene too, an introduction to adding filters to Zend_Search_Lucene. Also worth a look is the Search Tools in PHP presentation from phplondon.