MySQL has the flaw that all dual-licensed projects have; trademark is owned by a for-profit, all copyright is owned by a for-profit -- Oracle is the only one who can sell commercial licenses, Oracle has the privilege to sell commercial support as the owner of the only branch/fork of MySQL that is called "MySQL", all other forks will be forever called MySQL-forks, unless some alternative fork emerges that's so groundbreaking that it will make MySQL irrelevant (or all channels of distribution, like Linux distros, align to stop distribution of MySQL). Basically, as a project, MySQL is mature and has enough clout that it might never exist enough incentive for forks to gain market-share, ever.

That's one of the reasons why I switched to PostgreSQL -- BSD-like license, trademark owned by a nonprofit, has much better popularity and support than all MySQL-forks combined.

It removes any vague sense of the main corporate sponsor being in charge.

I don't think there were any forks as a direct result of the Oracle acquisition, but that's probably because there are several other prominent forks already and many of the MySQL people were displeased with the state of affairs under Sun, let alone Oracle. So most of the exodus had already occurred.

Check out MariaDB and Drizzle as starting points. :)

Heh, the thing is, MySQL was always open source, and Monty et al have all quit, so Sun really payed $1Bn of their shareholder's money that they couldn't really afford and the only actual asset they got was the domain name mysql.com. And people wonder why they were bought by Oracle...

it seems there are quite a few: percona's XtraDB, OurDelta, MariaDB, Drizzle are the first that come to mind, plus HailDB that is a fork of the single InnoDB