In my mind there are 3 things that are required for truly effective visual management. I call them the 3 I's (not to be confused with the 5 S's, 8 D's, or the 12 Days of Christmas).
Effective visual management can take many, many forms and must be suitably adapted to the process being managed. But I think that in any situation if you can satisfy the 3 I's you'll get the most out of it. I'd love to hear what you think about how to make visual management more effective.