Searchlight is a refactored version of the early experiment sphinx_views, an attempt to build a views-driven search implementation specific to Sphinx. Searchlight is designed to use search backends in a pluggable and interchangeable manner. There are currently two backend plugins available for Searchlight: Sphinx and Apache Solr.
The code was at http://github.com/yhahn/searchlight and has been committed back to Drupal.org.
Note: We are dropping Apache Solr support for D7 versions. Please use http://drupal.org/project/search_api if you need Solr.