When I saw the "1.5 miles of laptops" comparison I immediately searched the comments for the inevitable Library of Congress comment, and here I am. I agree that this is a meaningless measurement, simply because I don't know what "1.5 miles of stacked laptops" can compute. How many laptops can you stack in 1.5 miles? Are we talking about MacBook Pros or some fat HP notebook? Are we talking about folding at home results or are we talking about excel spreadsheets?
At least a petaflop is defined.
Now pardon me while I go back to writing a Library of Congress worth of code.