If things weren't accessible, how would you find them? At least in pure Perl, this would be impossible. You could iterate over all the symbol tables, following references to reachable objects, but this wouldn't find things that had leaked.
Comment on Re: Re: (MeowChow) Re: Looking for Leaks
In pure Perl, yes. In XS, it should be possible to iterate through the entire region of memory and see if anything has a valid reference. Also (and I'm stretching my memory here), isn't there a way in C to find out all the malloc'ed areas? You could compare that with the list of all reachable objects and see if there's a discrepancy...
------ /me wants to be the brightest bulb in the chandelier!