If anyone wants to have a play, I'm working on a new branch of my Lucene search engine plugin:
This branch uses the official Apache Lucene java code. It indexes around 50x faster than the current Zend PHP port, and I have it running searches in about 60us on a test database of 200,000 items. Sorry, no setup instructions as yet, but basically just have Java installed and run it on a linux box with port 8080 open and you should be fine.
Any code advice/criticism appreciated, in particular I'm not so sure how to go about letting devs acquire an instance of the Lucene class. At the moment I'm stuck with having a single default config set as a static, and using a static singleton method to get the singleton instance. I'd love to allow devs to use several instances with different configurations, probably via a registry / factory, unless anyone knows better.