Microsoft has made a dramatic statement about its future in enterprise search by introducing a free search server along with a licensed version, both of which align with search software already offered via SharePoint Server.

The company unveiled Microsoft Search Server Express 2008, which will be offered for free, and a fee-based upgrade called Microsoft Search Server 2008. A preview of Search Server Express that runs on Windows 2003 Server is available for download.

Both Search Server versions will be generally available in the first half of 2008, and both team with SQL Server on the back-end. Microsoft fully expects its partners to use the software to build stand-alone search appliances.

In addition, Microsoft plans to support the OpenSearch specification and use it to anchor a federated search environment that can integrate results from disparate search platforms.

The two new search offerings create an entry point and a midtier in a Microsoft enterprise search portfolio that previously included only SharePoint Server.

Microsoft is using a familiar model of seeding a market with a free tool to entice users to experiment and backing it up with a path to migrate to more full-featured versions. Microsoft used the model with SharePoint, offering SharePoint Services for free as part of Windows Server, and aligning it with SharePoint Server, a stand-alone content management, collaboration product and search engine with its own licensing requirements.

The two new search servers are based on technology baked into SharePonit Server.

Critics say Microsoft's strategy will disrupt in the short-term an enterprise search market that has Google and IBM, with OmniFind Yahoo!, offering no-cost or low-cost entry-level software.

In the long term, high-end vendors that integrate with corporate infrastructure and applications -- such as Autonomy, Fast Search & Transfer, Endeca Search and Vivisimo -- also could face pressure from Microsoft, the same critics conclude.

"Microsoft sees Google doing well selling search appliances, and it is clear there is some sort of inexpensive search thing that is desired [by the enterprise]," says Guy Creese, an analyst with the Burton Group. "But [Microsoft's move] is also part of a larger search strategy. You start with Express and oops, you need load balancing, and now you can move to Search Server and then you can move up to SharePoint Server. The strategy provides a lot of points where Microsoft can bring search into the enterprise. It's part of a long-term effort to make search part of the infrastructure."

Experts say Microsoft Search Server Express and Search Server will probably be judged initially as being "good enough" for divisions, departments or workgroups and will bring a new visibility to the enterprise search market.