MongoDB 1.6.0 is the fourth stable major release (even numbers are “stable” : 1.0, 1.2, 1.4, …) and is the culmination of the 1.5 development series.
The focus of the 1.6 release is scale-out. Sharding is now production-ready. The combination of sharding and replica sets allows one to build out horizontally scalable data storage clusters with no single points of failure.
A single instance of mongod can be upgraded to a distributed cluster with zero downtime when the need arises.
Replica sets allow you to setup a high availability cluster with automatic fail over and recovery. Replica pair users should, when convenient, migrate to replica sets.
Other Improvements in v1.6
Release Notes: http://www.mongodb.org/display/DOCS/1.6+Release+Notes
Now that 1.6 is out, we’re going to be focusing on 1.8. Help us prioritize features for this release by voting for your key needs at jira.mongodb.org. The #1 feature queued for v1.8 is single server durability.
Please join 10gen CEO and Co-Founder Dwight Merriman for the webinar What’s New in MongoDB v1.6 on Tuesday, August 10 at 12:30pm ET / 9:30am PT.