SQLWebpedia

Microsoft is coming out with a competitive product to Memcache, one of the most popular data caching products on linux. It looks like it will be free also and available this summer.

Summary from MSDN landing page:
Microsoft project code named “Velocity” provides a highly scalable in-memory application cache for all kinds of data. By using cache, you can significantly improve application performance by avoiding unnecessary calls to the data source. Distributed cache enables your application to match increasing demand with increasing throughput by using a cache cluster that automatically manages the complexities of load balancing. When you use “Velocity,” you can retrieve data by using keys or other identifiers, named “tags.” “Velocity” supports optimistic and pessimistic concurrency models, high availability, and a variety of cache configurations. “Velocity” includes an ASP.NET session provider object that enables you to store ASP.NET session objects in the distributed cache without having to write to databases, which increases the performance and scalability of ASP.NET applications.
The team blog for the product is at http://blogs.msdn.com/velocity
Solid Quality wrote up an article about it http://www.solidq.com/na/TechArticleDetail.aspx?Id=23