- Improved thread pool (--thread-handling=pool-of-threads --thread-pool-size=#), comparable to the closed source feature in MySQL Enterprise.
- KILL [HARD|SOFT] which allows you to decide how quickly you want a connection to die.
The state of MariaDB 5.5 is that we have just completed the merge with MySQL 5.5 and we are now testing the release. We will release it as a beta as soon as we have got it work with our extended test suite on all platforms; This may take a few weeks.
New features are added to MariaDB 5.6.