I was just going to post that in reading the letter it is so CLEAR AND OBVIOUS that Zawahari is in IRAN.
Wrong - The odds of either UBL or Zawahiri being in Iran are very remote - It makes little sense for either side - The Pak /Afghan/China border region gives more security without the need to be left as a pawn for a centralized Gov't (of which Iran definitely is) - That is not in AQ M.O. (and has never been part of UBL's).
As for Iran, housing Zawahiri or UBL is of no value to them - Only risk/cost - The only thing that comes from housing them is an assured U.S. military strike with full backing of the American public - This is the last thing Iran wants or needs (especially when trying to move toward a nuclear Iran) -
UBL (and most likely Zawahiri) remain in the border regions -