Regarding the matter of plagiarism, I applaud Steve Medema's
remarks, and note that I am also a journal editor who has had to
deal with these allegations.  There is an excellent source for how
they are dealt with in general by economics journal editors in a
paper in the JEL, June 2004, 42(2), 487-493, "Whose Line Is It?
Plagiarism in Economics," by Walter Enders and Gary M. Hoover. The 
results found in this paper are  somewhat discouraging, although 
there is strong support for a general code of ethics among economists.
      The paper reports some substantial disagreement about what
constitutes plagiarism, with use of an unattributed derivation of a
proof from a published paper being viewed as the most clearcut
case, although the case of an overwhelming simple reproduction of a 
paper is not presented as an option, perhaps because that is
viewed as being so absolutely clearcut.  Instead it offers a category
of "unattributed sentences (several)" that garners only 34% agreeing
that this is "definitely" a case of plagiarism.
      The responses to alleged plagiarism are all over the map, with
most editors agreeing that the original author (plagiarizee, if that is
not who is reporting the plagiarism) needing to be notified.  Beyond
this things get messy because of editors fearing lawsuits by those 
accused of plagiarism if the case is not clear cut, and also with some
concerns about possibly damaging someone's career, if the case is
not clear cut.  As an editor, I can say that I have encountered a range
of cases from those that do seem clear cut to others that are a lot
murkier and very far from clear cut.
     At a minimum, if there is any reason to believe plagiarism, one
should be banned from submitting any papers to the journal in 
question.  Beyond that, I think that it depends on the degree of
certainty, and the scale, of the plagiarism involved, with the case
of essentially wholescale reproduction of a published article by
someone else calling for the most stringent actions, in particular,
notifying the employers of the plagiarizer and notifying broader
relevant professional bodies.  However, there is an unfortunate
degree of fuzziness here, again tied to the fact that degrees of
the amount of plagiarism and degrees of the certainty of plagiarism 
can vary considerably.
      As a final note, the widespread scuttlebutt across many 
disciplines that I am hearing is that the current epicenter of
plagiarism is China, and it appears that informing superiors there 
may not do anything, as it seems to be viewed as an
accepted norm, particularly in that academic institutions may
themselves be getting credit from the government for numbers of
publications, and thus willing to look the other way, or even possibly
encouraging plagriarism that can be gotten away with, and often
involving submitting papers published in another language to
English language journals (and not always from the Chinese, with
me hearing of this happening in physics with papers originally
published in Russian and Korean).  Indeed, in the most recent
case I dealt with, where I informed the authors that they were banned
from submitting further papers to my journal, I got a rather snotty
and arrogant response, these being based in China.

Barkley Rosser