I use transactional DDL in my tests. All the tables, triggers, etc. are set up inside a transaction, and then the actual tests run inside nested transactions. At the end of the test run, the outer transaction gets rolled back, and everything disappears.
I don't know if it accomplishes anything truly new (other than ideas that aren't very useful in practice like being able to have multiple test runs going in parallel), but it's a pretty neat way to be able to do it and works well.
