I decided to take a look and play with MS "Velocity" Distributed Caching. “Velocity” is a distributed in-memory application cache platform for developing scalable, available, and high-performance applications. “Velocity” fuses memory across multiple computers to give a single unified cache view to applications. Applications can store any serializable CLR object without worrying about where the object gets stored.
Well I download the latest version CTP2 install it on 2 computers and it works very nice. Velocity supports the common cache types: partitioned cache, replicated cache and local cache. Depending on the type of data, applications can choose the appropriate type of cache.
On this version there are: Performance improvements, PowerShell integration, Additional Configuration Store options and native 64 bit support. Of course there is the ASP.NET Session State Provider that is very cool feature.
Presentations and Videos: "Velocity": A First Look, "Velocity": Under the Hood
You can read a lot more here.