The picture below was taken by Margaret on Sept. 26/04.  If you look at the top left corner, you'll see what seems to be part of a roof or something overhanging the Powder Magazine, but that isn't the roof that belongs there.  I'm not sure where it came from.
 

The picture below is courtesy of people at RiceBitz.com.  They took the picture on Sept. 26/04.  I've posted a close-up below it.  I have no idea what it is - I've never seen anything quite like it.