1) Providing a canonical URL for packages so that you don't have to mount them if all you want is to get access to their "library" pages, like developer-support. Example: /packages/(package_key).
2) Extend this scheme so that /some/url/ref/package_key/somepage serves up pages from another package. The point would be to let you reference, say, the permissions pages, or the notification-request page, without URL-wise having to leave the package/subsite you're in. I'm not sure this is the right solution.
3) Make apm_package_id_from_key return the _first_ package instance if there's more than one, instead of erroring out. That makes it okay to use this when you don't really care which one you get. Notifications, for example. (Save for permissions issues, of course. Hm.)