I was looking at Lucene .NET for a full-text search engine implementation but I was surprised to find out that the Lucene.NET application library is not open source anymore. It has been relaunched as a commercial product called SearchBlackBox. Lucene .NET is the core search technology behind the popular Lookout plugin for Outlook (later bought by Microsoft). Too bad that such a cool technology is not open source anymore. Atleast the developers could have left the last stable release of Lucene .NET under a public license. I'm not sure if there's any other open source search library for .NET in the market.
SearchBlackBox for .NET, is the full-text search engine library for .NET compatible with Lucene.Net and Jakarta Lucene 1.4-final. SearchBlackBox allows you to add full-text searching capabilities to all kind of applications from web site search to enterprise search applications. SearchBlackBox is compatible with .NET 1.x, Mono and Jakarta Lucene.
By the way, just to remind you guys that I've moved my blog to www.nilkanth.com. I may still cross-post once in a while. Have a nice weekend!