Diff'ing Explain Plans

Diff'ing explain plans is difficult and tedious.>Here is a new package function from Oracle for diff'ing explain plans
http://optimizermagic.blogspot.com/2009/09/whats-changed-between-my-new-query-plan.html
Of course I have my own ideas, some expressed here http://sites.google.com/site/youvisualize/sql-topology

but I will be outlining more visual ideas for sql plan analysis over this coming year.I have some exciting designs we are implenting in DB Optimizer (http://oraclemonitor.com)