After Fedora and OpenSUSE have switched from MySQL to MariaDB, Red Hat has announced that they will do the same thing.

Starting with RHEL 7, Red Hat will replace MySQL with MariaDB, as the default database. And the next in line to switch to MariaDB is CentOS.
MariaDB is a fork of Oracle’s MySQL.
This is what one of the RHEL developers said:
“I presume there is not much love lost between Red Hat and Oracle (particularly since the “Oracle Linux” stuff started) but I’m pretty sure this move won’t make Oracle any happier […] Thus it’s a serious move in political terms.”