Let's see if I can organize my idea well enough to get it across.
What I have right now are about 20 different Header menu's (they are images maps). However they are transparent pngs that are used in conjunction with the backgroound image to look good. So, I made some additions/modifications to the tpl files so this would work. I'm telling the templates to retrieve the named PNG header menu depending on the name of the Category, for example if my category is called WORLD NEWS, the png image retrieved in called WORLD NEWS.png.
The problem with your method is that, as aformentioned, there are about 20 categories and 20 respective header images. I don't think it's good to make 20 tpl files >_>. (Not to mention the home page header too)
That's why I was hoping for a way to get vivvo to tell me if it is in a category or not. It DOES work if the user is in a category but it doesn't work the other way around. Or maybe I just haven't figured it out.
If you want to see some of the code and or website i can pm.