SnowValley have release their free MCMS.Search which provides a complete open-source search solution for Microsoft CMS based around the high-performance Lucene search engine.

Features include:

• Indexing of a site's HTML content
• Full text indexing of PDF and Word attachments
• Indexing of metadata
• Support for simple and complex search queries
• Logging of search terms used on a site for later analysis

There are 2 components to MCMS.Search:

• A spider component that indexes a CMS site
• A search component that executes searches against the index

Download : Live example implementation