A Solver Foundation program is a declarative model embedded in familiar NETfx design patterns and development environments (Visual Studio 2008). The model is embeddable in any supported Solver Foundation context, from Excel 2007 to C#, F#, or any other CLS compliant programs.
Microsoft Solver Foundation is a brand new framework and managed code runtime for mathematical programming, modeling, and optimization. It is designed to run on NETfx 3.5+ and is completely implemented in C#. Solver Foundation is useable from all CLS-compliant languages, including F#, IronPython, VB.NET and C++. It is also available via a visual, Add-in Designer for Excel 2007 users. Solver Foundation provides solvers and services for modeling and solving to a broad community of users: from Excel users and analysts to programmers working on business critical scheduling, configuration, risk management, and planning solutions. It provides services for model checking, parallel solving and workload scheduling, model interchange, and declarative data binding via LINQ and other NETFx technologies. As an open framework designed for third party extensibility, it exposes facilities for users to plug-in their own solvers while still leveraging all of the modeling services and capabilities of Solver Foundation.
Go and download the bits from the MSDN Code Gallery