FWIW..

This looks to me like a first revision which was intended to be developed further. As mentioned by hardburn the for ($@) sets $_ to the value of $@. Why would we want to do that? So we could then do something like:

eval {

 # bla bla
};
for ($@) {
   /NOT FOUND/ && do { 
                      print 'Where'd I put that?';
                      last;
                     };
   print 'Na,ah. Not for you!' if /FORBIDDEN/;
}
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Each of those is testing the string value of $@