Comment 8 for bug 611495

It is still happening with 0.87.
It is not really the packaging question - you simply cannot do, what you'd like to do, during package uninstallation - the whole process is ran as the root user, and there is no way to reset gconf settings at this point for users. I'll try asking some folks about it, but for now I don't see a clean solution. Metacity should really be smarter, and fallback on gnome-screenshot, if it allows changing this setting.