McAfee MySQL Audit Plugin
I'm work at McAfee at the moment and I stumbled across this:
They have a free (GNU General Public License according to the download) MySQL plugin for auditing MySQL - https://github.com/mcafee/mysql-audit/downloads
(yay, for using github)
They also have an enterprise-level database security product which of course is not free (no idea how much) and a video explaining what it does can be found here.
Another MySQL security company is, of course, GreenSQL with their open source and commercial SQL firewall.
I did evaluate GreenSQL once and recommended it to my boss at the time, but his reaction was:
"Well, its your job to secure MySQL, innit?"
Hopefully, other DBAs will have more luck then I had recommending security products where security is important.