2009-11-06 38 -78
The hash appears to be located about 3/5 mi east and about 400' down the hill from Skyline Drive, in some woods. (Yes, imperial measurements- it's a US hash.)
Quite possibly Spi Waterwing and several of his friends.
 Spi Waterwing
One of Spi's friends had planned a get-together in a nearby town; all of the invitees were xkcd fans. They may decide to head up Skyline Drive to the hash.