Not if you used frames. Then you could have the new site incorporate all the others without changing them at all. Plus, that way people who want nothing to do with it can just keep using the addresses to the actual forum/blog/wiki/whatever and not get a frame shoved down their throats, and without needing cookies to "save" the setting.Using this feature means a page modification for all Puppy sites
On the down side, using a frame would mean you get that much less viewing space, since you can't just scroll away from them. I didn't work with frames for very long back in my web-coding days, so I don't know if it's possible to set up a chunk of javascript to 'collapse' a frame by resizing it. If it is, that would be cool. I know that the frames can be set as manually resizable as long as you don't make the border invisible. That's a little ugly though, unless you can apply style-sheets to them. I got into CSS after I stopped using frames so I'm not sure if you can do that. I know you can use CSS on forms and such, so I wouldn't be surprised.
Anyways, as a worst case scenario there could be a link on the upper part that sends you to the actual page without using frames, like Google Images uses. And every browser I've ever used also supports right-clicking and choosing "view this frame only" or some such thing.