MongoDB 3.3.6 has been released as a development release and is not intended for production use, marking the beginning of the evolution into version 3.4. This new release includes several improvements to aggregation operators, including $split and $findChar, and introduces new commands such as `dump lock manager state` and `$unwind`. Additionally, changes have been made to error messaging and Jepsen testing, ensuring better stability and reliability for the database. The MongoDB team invites users to report any issues found with this release.