Google added a feature to Webmaster Tools yesterday that I hope will find its way in to Business Listings and other services. Now, if you are verified owner of a website, you can simply add additional users to the Webmaster Tools account (through the verify link). This means site owners can add individuals that do development, marketing or optimization, without having to upload additional files or edit pages. This greatly simplifies things, giving owners a simple way to remove this access.
More on this from Google here