All Connections content should consistently leverage the Notify function. Some content types (Forum, Wiki, etc...) don't support it a all.
Also, IF user is the content owner, allow them to explicitly Notify. Example: Private Bookmarks. I often create Private Bookmarks that I don't want exposed to the enterprise. However, I do want them shared with a specific community(s). I can accomplish this at creation time but, can't follow up an notify an individual community member at a later time.