It was announced that MariaDB is now the default implementation of MySQL in the newly released Red Hat Enterprise Linux 7.
News of the Red Hat Enterprise Linux 7 can be found here.
And mention of MariaDB replacing MySQL as the default implementation is referenced in their release notes here.
The full change log entry reads:
MariaDB 5.5
- MariaDB is the default implementation of MySQL in Red Hat
Enterprise Linux 7. MariaDB is a community-developed fork of the
MySQL database project, and provides a replacement for MySQL.
MariaDB preserves API and ABI compatibility with MySQL and adds
several new features; for example, a non-blocking client API
library, the Aria and XtraDB storage engines with enhanced
performance, better server status variables, and enhanced
replication.
Detailed information about MariaDB can be found at https://mariadb.com/kb/en/what-is-mariadb-55/.