lego_maniac - 10:52 am on Mar 6, 2005 (gmt 0) Here's some discussion about pagejacking, 302's, and dupe content penalty.
Are some of these harmless?
That depends on the method used to do the redirecting, and of course the intent of the site doing the redirection. The general concensus is that 301 redirects (Moved Permanetly) are okay, but 302 (Moved Temporarily) and meta-refresh is detrimental. Why they are treated differently, I'm not sure.
Here's some discussion about pagejacking, 302's, and dupe content penalty.