Bertrand Delacretaz at XML.com - Solr: Indexing XML with Lucene and REST:

"Solr (pronounced "solar") builds on the well-known Lucene search engine library to create an enterprise search server with a simple HTTP/XML interface. Using Solr, large collections of documents can be indexed based on strongly typed field definitions, thereby taking advantage of Lucene's powerful full-text search features. This article describes Solr's indexing interface and its main features, and shows how field-type definitions are used for precise content analysis."