I’m pleased to announce that we're unveiling Microsoft Search Server 2008 today at the Enterprise Search Summit in San Jose! The really exciting news is that we're also offering a free version of this product – Microsoft Search Server 2008 Express – which you can download now as a release candidate. Our team worked extremely hard to get this release to you, and we’re proud of what we’re delivering today.
Our aim for Search Server Express is to give you a free and powerful enterprise search product that’s incredibly easy for you to deploy. After you download it, you’ll find it takes just a few minutes to get it up and running. It’s going to be the fastest way you can bring an enterprise search experience into your business.
Source : Microsoft Enterprise Search Blog