Probably not a major hint, but something interesting I just noticed, as well as how to fix it.
During my time with a developer copy of Leopard (about two months), I noticed that the printer icon would remain in dock after a print. I just never thought about it much until today, when I was cleaning up the Dock after loading the final release of 10.5. If you control-click the printer icon and select Auto Quit from the contextual menu, the printer icon will then disappear when future print jobs complete.
Again, not a major hint, just an interesting thing that I would have thought would have been enabled by default.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20071030064059756