I see 150 mils (0.15 inch) spacing between the headers in question on the Eagle .brd file for the Mega2560
The one I just unpacked from that tiny box is ..well...... PERFECT!
I would love to see some pictures of it
(if I see any Morse Code will let you know).
I think this mystery has been solved now...
the .BRD file currently downloadable from arduino.cc has apparently been fixed, and has the 160 mill separation
Has anyone found the source code for the Morse?