This is the same sort of thing they use for the scanpyramids project right? They detected a large void in The great Pyramid but have not yet confirmed it is there. They are fairly sure the scan is accurate as they also detected another void that has since been confirmed. It is kinda cool.
Edit:
"By comparison, muons have been making headlines in recent years for their ability to help us look deep inside volcanoes, peek through pyramids and see inside cyclones. Muons fall constantly and frequently around the world (about 10,000 per square meter per minute) and can't be tampered with. "
Spose If I had jut read this bit, I would have my answer. Cool stuff :)