A quick bit of explanation (and thanks to Pete Weiss, who 
cleared this up for me off list): my problem was that my lists 
(like all 14.4 lists) were private by default, and taking 
"private" out of the configuration line didn't change that.  I 
had to put "public" in the line -- and after that, the addresses 
were masked (except to subscribers with a password). Which is 
what I wanted.

And about this:

> I'm glad that you cleared that up that the described behavior
> is seen only in "public" lists; all my lists are "private."  I
> am puzzled though as to how one "logs in" to a public list
> archive, and what the point of doing so is. 

You use the same password as to change your preferences via the 
Web interface, and the only point of doing it would be to 
recover the masked email addresses so that you could write to 
someone off list.

This is valuable for lists like scholarly discussions, where the 
archives might be valuable for others not subscribed: before 
this masking was enabled, I had to have the archive private, and 
the only way I could refer someone to a discussion was to get 
her to subscribe to the list and then set up a password. Now I 
can make the archive public and not worry about addresses being 
harvested.

-- Russ
St. Thomas University
http://www.StThomasU.ca/~hunt/