I dropped by the ADO.Nets team stands at TechEd 2008 and saw a demo of a new project called "Velocity". It is a distributed caching technology, that allows in-memory caching across a distributed set of machines that is resilient and fast.
Although not on schedule for RTM release until 2009, this technology hold promise for scenarios like distributing reference data, and session state across multiple machines in a server farm.
Anil Nori and Muralidhar Krishnaprasad presented a session on the topic and posted their TechEd slides here. Here is the "What Is slide" -
More resources -
The Velocity team blog
Velocity Project Page
CTP 1 Download
Troy.