In ArcGIS Online, "share" settings seem to only intend for others (groups, etc) to have access to VIEW a map. Is there no co-editing version of sharing? Of course, this isn't Google Docs - it's important to communicate with others in a team about adding and saving features when two or more people are logged in to the same account working on a project. You don't want to overwrite, or undo, anything done by your partner. If users with distinct login credentials are to collaborate on something (map and/or presentation) simultaneously, the same caveat will hold true. However, is it (or will it) be possible to share editing privileges with another individual?