Colaborativa.net has released Kneobase, an open source "enterprise search" product. It can accept many data sources as searchable elements (and in multiple languages), and can provide search results in multiple formats, including SOAP, which might make it a good search engine for use in a service-oriented environment, because it doesn't need search indexes published to a web server.
Kneobase offers many features for searching, like language auto-detection and search by file type, and allows federation of many distributed content sources in a single textual index.
Kneobase is a web application based upon Lucene and the Spring framework. Its API for searching and discovering is a SOAP web service, making it compatible with SOA architectures. As a .war, installation can be as simple as deploying the .war file in a J2EE application server or servlet container.
