Microsoft has announced a new NoSQL Database named "DocumentDB" as a part of their Azure Service. Microsoft Azure DocumentDB is a document-oriented, NoSQL database service designed for modern mobile and web applications.
Azure DocumentDB supports JSON documents enabling easy iteration of application schema. Deep integration of JavaScript also allows developers to execute application logic efficiently directly within the database engine.
Benefits
Ad hoc queries with familiar SQL syntax
JavaScript execution within the database
Tunable consistency levels
Fully managed
Elastically scalable throughput and storage
Open by design
For more info,
http://azure.microsoft.com/en-us/documentation/articles/documentdb-introduction/