Based on the comment you made to Diego, your question is a lot different than what it looks at first sight.
If you require a lot of interaction, then don't offer a notification each time, and don't save each action immediately.
Instead, create sessions where the user can do any amount of actions (you can autosave every X amount of minutes). In these sessions, allow to undo everything, and for each action performed use a subtle animation/transition so the user understand something happened. This information transmitted by the transition should be enough to convey the message.
After the user is happy with the changes, offer to save the changes as in any other app, and then display a "your changes have been saved" message.
By doing this, you won't overwhelm your users, you'll keep then informed of their interactions and you'll have one and only one notice for what is a single process (content edition).
Taking the Gmail example by Ken Mohnkern : just imagine if every time you perform an action when creating an email (editing, deleting, changing fonts, etc) you get a message. You'd be alienated in no time. Instead, all those actions are just subsets of the main action: send a mail. Thus, you get the message only when you send a mail or create a draft, not every time you perform an action.
Use messages sparingly, and always try to define what the main action is, paying special attention to destructive actions