Okay, so I'm trying to be snarky. But since this blog occasionally attempts to be useful:
Printing in Flash has always been inconsistent, poorly implemented, and plain broken. As of Flash 10.1, it got some big updates to the point where it's actually useful.
You still cannot print vectors with transparency -- in which case you're forced to bitmap them first. You still cannot print bitmaps without them looking like shit. You cannot render decent quality bitmaps without using more memory than god.
But printing now works consistently (even if terribly) across platforms; vector printing really works now; and you can spool pages across frames (meaning a potentially unlimited number of pages, no longer timing out, and being able to show an animation and update progress while it chugs along). I can post code some day -- if there's demand.