I'm sorry, unfortunately I didn't think that all through before answering. Adding tabs is mostly done client side which is hard or even impossible to intercept. And those plugins that add a new tabs usually have their own skin templates that would not fit into the iframe you have for "regular" preferences.
In short: I guess there's no way around a custom hook defined by your plugin which is explicitly used by the other plugins you want to gather.
I figured. Is there a reason that 'tabs' are done client side? I can sort of understand from the classic perspective, but in larry the tabs are much more useful and we should maybe encourage its use more. Would be cool to add tabs through a normal PHP hook, and even cooler if you then also get section support automatically (if you want it, some plugins may want to use the full page).
Cor