Here's a solution using Date::Parse:

use Date::Parse;

while (<>) {
  chomp;
  my @t = strptime($_);
  my $d = sprintf("%d/%d/%d", $t[3], $t[4]+1, $t[5]+1900);
  print "$_ -> $d\n";
}
__END__
June 12, 2008 -> 12/6/2008
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Some caveats: Date::Parse only recognizes English month names and follows American conventions for things like 12/6/08 which parses as December 6th, 2008. Otherwise it will recognize most variations of specifying dates, e.g. (12 Jun 2008, 2008-06-12, etc.)