> I have a feeling PPS got a patent for the idea.

Any idea where to find this patent? I'm not too concerned about this patent
(if it exists) as there are various other ways in which the same effect
(being able to attach external properties to objects) can be achieved. Using
ephemerons is just a very convenient way of doing it as you don't have to
worry much about the relations in the graph of objects.

Cheers,
  - andreas