History repeated
This thread is almost exactly the reason why I started looking at SSI style clustering, and back then Mosix in particular , well. ages ago :) Things evolved but even with MigSHM in place a SSI style cluster doesn't solve your problem when you try to scale a database.
But how DO you scale a database ? Things have become a bit more easy lately when you combine MySQL-Cluster with LVS , however we still need to figure out a way to do similar stuff for large databases. We really really need this disk storage feature for MySQL cluster some day :)