I setup a MySQL 5.0 Cluster on a spare server with multiple Xen VMs and discovered that Drupal 6 (and most likely D7 as wel) as it exists today cannot function properly under the MySQL NDBCLUSTER engine. It seems that under the NDBCLUSTER engine (also known as NDB), D6 has a table called menu_router that fails to be converted.
I posted a bug report about it under the D6 platform as it is rather detailed, but I have an idea this will affect D7 as well.
http://drupal.org/node/391130