[Zope-dev] Getting User Information

Hi, I'm trying to work out how to get user information from a PAU folder in Zope 3. When a user views or adds a page I either need to lookup the creator or the current user and get their standard information (such as full name, email etc). I can see how to do that from the API - getPrincipal(id) - but what I am wondering is how I can find out dynamically how to find out where the PAU is. I guess I should be able to lookup the object using the fact that it has been registered, but I don't know how to do that, nor where to start looking (I've done quite a few google searches). Any help/pointers would be much appreciated. Thanks, Rowan