Do you recall, while porting the SSD test from DB2 to PostgreSQL (see, I'm even capping as one is supposed to), that I lamented not being able to write out rows to multiple tables in a Common Table Expression?? DB2 can't either, nor have I yet confirmed whether any ANSI level, including 2003, specs it.
But I've just found this presentation for PG. And here's a test of it. Boy-howdy. Finally, a feature that DB2 doesn't have; well soon, maybe. In any case, have a read, it's really cool.