About that 6 digit google gps coordinate, I stared at it sometime back and suspected it is just software engineers not knowing what a gps can do. I was right:
http://wiki.xkcd.com/geohashing/GPS_accuracy
I think getring 5 digits is already asking a bit too much;) 6 digits will be asking for 10 centimeter accuracy. Not sure if millitary can get that good.