The new HD PENTAX-D FA 21mm f/2.4 ED Limited DC WR lens is now available for pre-order (available in black and silver color):
It seems that the lens cap is sold separately for $45.
Previous coverage of the new HD PENTAX-D FA 21mm f/2.4 ED Limited DC WR lens can be found here:
HD PENTAX-D FA 21mm f/2.4 ED Limited DC WR lens officially announced
A message from the development team of the new HD PENTAX-D FA 21mm f/2.4 ED Limited DC WR lens