Social impact of annotations?

(This list has not been very active lately; let me know if discussion
of Web annotations has migrated to a different forum and I can repost
my question there.)

What, if any, will be the social impact of widely deployed third party
Web annotation technology?  By third party I mean annotations that do
not require the cooperation of the original Web Site provider.  So for
example, I would not consider a link that a Web Site puts up to a
hypermail discussion list to qualify as third party annotation.  In
contrast, I would consider Netscape's Related Links functionality to
be a kind of third party Web annotation.  

-Rolf

-- 
| Rolf Nelson (rolf@w3.org), Project Manager, W3C at MIT
|   "Try to learn something about everything
|             and everything about something."  --Huxley