Today Microsoft unveiled their enterprise search lineup for 2008:
Microsoft today announced Microsoft Search Server 2008 Express — a downloadable Enterprise Search product available at no charge that combines simplicity and ease of use with a powerful set of search features. Microsoft Search Server 2008 Express joins Microsoft’s Enterprise Search lineup, which is built on the Microsoft Office SharePoint Server 2007 platform.
A release candidate is available today for customers to download and evaluate the product at http://www.microsoft.com/enterprisesearch.
Additionally, we announced Microsoft Search Server 2008, a sister offering available through our volume licensing program that contains advanced deployment and scalability options.
Apparently both products are based on technology pulled out of SharePoint Server for Search 2007 which will be superceded when the two flavors of Search Server 2008 ship in the first half of 2008.