You may be interested in the following article:  "Whose Line Is 
it?  Plagiarism in Economics," by Walter Enders & Gary Hoover, JEL 
42(2), pp. 487-493, 2004.  They start out with an anecdote about 
finding, as a referee, a case of plagiarism, which ended in no action 
except rejecting the paper.  They then report on some survey results 
of editors and the profession and discuss a few examples.

One famous example was in the QJE in the early 1980s.  They conducted 
an investigation and re-published the whole paper under the correct 
author -- see vol. 99 no. 2, 1984.

Spencer Banzhaf