The coordinates for this date are:
0.4002468981550087, 0.7227718731909889
Coordinates
2008-05-23 in Boston graticule -- The coordinates in Boston are on the edge of a large, sandy region next to the Wachusett reservoir, which Randall may attempt to reach if only to figure out just what it is. Perhaps part of a tree farm?
2008-05-23 in Malone graticule -- Glub, glub, it's a scuba meeting for us.
2008-05-23 32 -117 in San Diego, CA graticule -- Craig has no boat, no scuba license, and no underwater camera.
2008-05-23 in Ottawa graticule -- We claim this residential parking lot and backyard in the name of XKCD...about 4 blocks from the workplace. Video camera footage to appear on youtube soon.
2008-05-23 in Puerto Rico graticule -- Today's location is only 6 miles from the Arecibo Observatory!