That was one of the things that was sadly dropped in the redesign of the printing functions from Rhapsody to Mac OS X. Yeah, it would be nice to see that added back in... but I highly doubt that Apple would do it in 10.4.10... It is a change better suited for the 10.5.0 release.
Yes, you're right. It would be something that would be included in a major OS release, not a service update.
I'd like to be able to to launch the printer setup utility, select a printer, then click on "Print a test page" in the toolbar. That would be a nice thing, especially when one must deal with several networked printers.
Any reason the Mac OS can't have the best looking printer test sheet in town?