The document discusses the development of node-mdb, an open source emulation of Amazon's SimpleDB NoSQL cloud database using Node.js and the GT.M database. It describes why the author chose to emulate SimpleDB, use GT.M as the database backend, and develop it using Node.js. It also provides details on how node-mdb implements the SimpleDB APIs by mapping the database schema and operations to GT.M globals and leveraging Node.js asynchronous programming patterns.