Microsoft Velocity provides distributed in-memory web application caching. This provides highly scalable, high-performance application caching. “Velocity Caching” can be used to cache any Common Language Runtime (CLR is the Virtual Machine of Microsoft’s .NET initiative) through simple API’s. From a general standpoint, Velocity was created with the goal of providing performance, scalability and availability.

The main application for providing scalable, available, high-performance applications using Velocity is by fusing the memory between multiple computers to give a single/unified cache view for the application to employ. The application can they store any CLR object that is serializable.

http://blogs.msdn.com/velocity/