I always enjoy reading Microsoft tech announcements simply because they just seem to "nail" business requirements and building the proper solutions / technology.

The quote the announcement: "Distributed cache is becoming the key application platform component for providing scalability and high availability. In-memory caching has been traditionally used primarily for meeting the high performance requirements of applications. By fusing caches on multiple nodes into a single unified cache however, the distributed caches offer not only high performance, but also scale."

Microsoft released a first CTP (technology preview) of their distributed caching technology called Velocity:

From the readme: "Velocity" distributed cache is provided in the form of a cache cluster, simplifying your application code by managing the complexities of load balancing behind the scenes. When you use "Velocity," you can retrieve data by using keys or other identifiers, called tags. "Velocity" supports optimistic and pessimistic concurrency models and a variety of cache configurations.

For those familiar with memcache (open-source), it's the same type of solution. Velocity however seems to be a much more enterprise ready package with advanced caching features.

It's further interesting that Velocity uses ports: 22233 (data) and 22234 (monitor cluster nodes), looks like we're going to need a distributed caching 'RFC' and protocol some time soon.

The full announcement is here:
http://blogs.msdn.com/velocity/archive/2008/06/02/introducing-project-codename-velocity.aspx