Neato. Solr is an Apache incubator project that turns Lucene into an enterprise search server. The cool thing about Solr is that it has an exceedingly pleasant RESTful web services api. To quote the FAQ:
Solr itself is a Java Application, but all interaction with Solr is done by POSTing XML messages over HTTP (to index documents) and GETing search results back as XML, or a variety of other formats (JSON, Python, Ruby, etc...)
Cross platform. Flexible, powerful, extensible, full text search. Easy to program aginst. What's not to like?