MongoDB version 2.2 has been released with over 1,000 new features, bug fixes, and performance enhancements, focusing on improved flexibility and performance. The Aggregation Framework is now available in its first production-ready release, making it easier to manipulate and process documents without separate application processes. Additional "Data Center Awareness" functionality enables geographically distributed contexts, while improvements to concurrency eliminate the global lock and enhance parallelism in write operations.