The NoSQL database MongoDB has released a major new 2.2 release. Interesting new features include tag-aware sharding, read preferences, and removal of the global lock.
For a high-level view of the new release, see this blog entry.
For more details, try the release notes, which have many pointers to additional resources.
There's a wiki page for tag-aware sharding.
For a completely content-free interview with the CEO, try this Wired article: NoSQL Pioneer MongoDB Doubles Down on the Data Center