A few editorial comments:

• I see funny characters here:

  log => Log::Log4perl->get_logger(’Authen::Simple::PAM’)

• I suggest changing this:

  In my environment, a password will fail even if it is correct if it contains a slash unless that slash is escaped with a preceeding slash. I replace all slashes with double-slashes in your password to keep this from being a problem. I don't know if this is portable, a good idea or profoundly dangerously insane. If you don't want this to behavior, set this value to false.

  
  To this:

  In some environments, a password containing a slash will fail unless the slash is escaped. Set escape_slash to true to escape slashes in passwords, or false to leave them unescaped.

• Two typos:

  "... obvious choice beinga ..."
  "... do a successfull..."