This post on the OSX World Forums points to this article with the rumor that Mac OSX 10.3 (Panther) might include “piles”:
Mac OS X 10.3 will finally see the implementation of the “piles” interface concept patented by Apple back in the dear, dead days of Copland but never delivered to the desktop. The feature, which has been lobbied for by Bruce Tognazzini and other interface curmudgeons, is designed to ease the clutter of windows in the Finder: The Blade’s sources indicate that extraneous windows will shrink and jump out of the way automatically, rearranging themselves into scaled-down tiles in response to the user’s movements.) […]
Cool! And if Tog likes it, I look forward to the feature all the more. Of course, it’d help to have a Powerbook as well ;).