With a bit more information on the MySQL clustering front, there's this new post from Blane Warrene on Open Sourcery.

I wrote briefly about securing MySQL last week and Andrew-J2000 suggested he was looking for a bit more depth into the clustering side of the scenario. I have recommended some additional links here for night-table reading to study up on some case studies, documentation and other miscellany involved with clustering MySQL.

He links to a few different pages from various places, including a nice little HOWTO which includes configuration and security tips by Alex Davies.