Also, there will be a central repository of plugins, both official and user-created. (Part of the incentive to allow the computer to phone home and verify its registration is that the user will be notified of new plugins for download.) Is it reasonable (with the user's explicit permission, of course) to download these to the desktop and allow the user to deposit them wherever he or she wishes? Or is it preferable to download them directly to where they belong, perhaps by using user defaults? In particular, I'd like to leave it up to the user whether to use the system-wide Library or the user-specific Library.