The official MySQL server returns version string like this:
5.5.25-log
While (latest stable) MariaDB:
10.0.17-MariaDB-1~wheezy-log

Some old and crappy CMS installations break with the MariaDB string above, like Joomla til API17:

  public function hasUTF()

  {

    $verParts = explode('.', $this->getVersion());

    return ($verParts[0] == 5 || ($verParts[0] == 4 && $verParts[1] == 1 && (int)$verParts[2] >= 2));

  }

MariaDB is told to be a drop-in replacement for MySQL. In this case it is unfortunately not true. Patching the already installed webapps is usually not an option for administrators.

For this reason I recommend to add a new configuration option, something like this into mysqld section of the config file:
fake_version=5.5.25-log

With this option set, MariaDB could return the faked version string.