I want my scripts cached a certain way for a certain thing and my deployment systems do take care of all that. Given that situation - the only thing pagespeed was adding for me was serving pages through google's CDN. However, the upstream connection from google to my server was pretty poor and for most cases it ended up ADDING latency! :(
So for now, I'll give automated 'page-speed' tools a pass and simply try and do each step that Y!Slow suggests manually.