Why would anyone want to overload the & (address-of) operator?

If you're dealing with any sort of wrapper objects, you might want or need to transparently forward the access to the wrapper to the contained object. In that case, you can't return a pointer to the wrapper, but need to overload the address-of operator to return a pointer to the contained object.

Because they're evil and want you to suffer.

Or I guess if you are using proxy objects? I suppose you might want to return a pointer to the managed object instead of the container - although i'd rather do that with a getter function. Otherwise you'd have to remember to use things like boost::addressof.