We are pleased to announce the immediate availability of MariaDB 5.5.21-beta. MariaDB 5.5.21 is the first Beta release in the 5.5 series and follows the initial MariaDB 5.5.20-alpha release. We hope to follow it up soon with Release Candiate and then Stable (GA) 5.5 releases.
MariaDB 5.5.21 beta is a merge of MariaDB 5.3 and MySQL 5.5 with some limited additional bug fixes. In this release we have added some extra notable features including an improved thread pool, an updated SphinxSE storage engine for fulltext search, and the ability to selectively skip replication of binlog events. Extra features planned for MariaDB 5.5 will be pushed into subsequent releases.
As with any beta release, MariaDB 5.5.21-beta should not be used on production systems.
The Release Notes page has some notes on the release. There is also a Changelog available for those who are interested.