Activity data - sharing if multi company how will that work?

I have been reading through the 2007.0 docs (in the support centre) which looks really awesome BTW.

One thing which did not seem addressed is the lack of ability to create secure sharing groups for task information, eg: sales people see what their tasks but not the sales managers tasks etc (I am a broken record ).

So then I'm reading about the multi location entity feature and I'm thinking how bizare it would be if I was a user at one subsidiary browsing through the tasks of another subsidiary, I guess that "private" tick box is going to get a real workout!