I'm getting the impression that the loud and popular "free" database, MySQL, is still several years behind practically everyone else. Including the other "free" database, PostGres. I don't think The Powers That Be will be at all interested in changing the database. :-/
MySQL is popular because it is fast and easy, but it is least SQL compliant of the popular databases. MySQL 5 seems to move it up a lot terms of SQL compliance and adds some key features, but I have not had a chance to play with it much. MySQL's popularity is really grounded in the fact that many low cost web hosting companies support nothing but MySQL.
Jay