Thomas wrote the Sphinx search module nearly a month ago. I have just now gotten to looking at it. From the things I have read, Sphinx looks really cool. I am considering using it in some other sites.
Sphinx is a "standalone search engine, meant to provide fast, size-efficient and relevant fulltext search functions to other applications. Sphinx was specially designed to integrate well with SQL databases and scripting languages. Currently built-in data sources support fetching data either via direct connection to MySQL, or from an XML pipe."