Martin Fowler has this great ability of explaining potentially complicated stuff in an easy to understand manner. Moreover he is the ultimate pragmatist. He provides real life examples that helps explain the concepts he talks about and does not get emotionally attached to any technology 🙂
This is an excellent talk Introducing the emergence of NoSQL and the rationale behind the use of products such as MongoDB, Cassandra and Neo4J. One of the key points mentioned is, although NoSQL databases will play a major role as a persistence technology it will most likely be used in combination with traditional Relational databases in many (enterprise?) scenarios. This is known as Polyglot Persistence.
Watch this brilliant talk to get a better understanding of the basic concepts behind NoSQL DBs, the rationale for using them in software development and the trade-offs of using them compared to RDBMSs.