Since we are covering about memory, the following news article is timely:

http://mashable.com/2011/10/17/ramcloud/

John Ousterhout, research professor of computer science at Stanford and head of a new project called RAMCloud, proposes exactly that: Create a data center storage solution “where information is kept entirely in DRAM and large-scale systems are created by aggregating the main memories of thousands of commodity servers.”

Here is a more technical Wired article and the original white paper.