Interesting that all of a sudden this topic comes up after a two-week hiatus,
but, since it is, here is an experience that has been mentioned on another
list.  The list in question is a dog related list which is hosted (along with
many other simular lists) by a server owned by a publisher of dog books.
The author that was making the comment had been giving training advice
on one of the lists.  The publisher regularly makes updated editions of their
works and in the next update the exact text from this author's detailed
advice showed up in the publication without any credit as to the source.
Since this person has published her own work in the past, she read and
responded to this "oversight".  Now, what happened after that I don't
know (I unsubscribed from the discussion shortly afterwards) but the point
that the author made was that the publisher neither made mention that they
would take messages from lists hosted on their server, nor did they say
they wouldn't.  Her action (besides contacting the publisher) was to NOT
post to the list and take to private her correspondence any discussion.  It's
been about five years since this came up, and I do not know the end results
of her actions, but it has always been in the back of my mind when I post
to any list.  With one of my lists there is often good material that could be
published commercially - but the audience is very limited and so would be
any profits from compiling the information.  I have written in my welcome
message and have used bottom banners that say something of the sort, "all
messages copyright the original author and may not be reprinted or
forwarded without permission" - for all the good it would do in this area.