It will not add new ponies in your piggy bank,
but will give us opportunity to refuse in the future from obsolete php mysql extension.
Currently new code will work ONLY if you manually add in config.php option:
$config['db_extension'] = 'mysqli';
Also now added some new configurable options for db connections:
$config['db_extension'] = 'mysqli'; // The PHP MySQL extension to use ('mysql' or 'mysqli')
#$config['db_port'] = ''; // MySQL port (leave blank for default port: 3306)
#$config['db_socket'] = ''; // Path to the socket (leave blank for default socket)
#$config['db_persistent'] = FALSE; // Whether persistent connections should be used or not. WARNING use at own risk!
#$config['db_compress'] = FALSE; // Use compressed protocol for the MySQL connection