Something to investigate over the summer break, NoSQL:
Next Generation Databases mostly address some of the points: being non-relational, distributed, open-source and horizontal scalable. The movement began early 2009 and is growing rapidly. Often more characteristics apply as: schema-free, replication support, easy API, eventually consistency, and more. So the misleading term “nosql” (some call it “not only sql”) should be seen as an alias to something like the definition above.
I’m particularly interested in the schema-free variety of NoSQL databases, like the Apache CouchDB project. However, this is just one variety of NoSQL.
Hat tip to Redmonk.