it's "hidden" by pushing it way off to the side using CSS
from: style.css on the site in question
#information{position: absolute; z-index: 10; visibility: visible; left: -1000px; top: -1000px;}
While I think Google won't penalize them without it being SPECIFICALLY reported as a spam site, it's definitely at the lower end of food chain, as it's pure keyword stuffing using "hidden" text - something that google frown upon and one of the techniques they ask about on their spam result reporting page;
http://www.google.com/contact/spamreport.html
It is a technique that is very hard to detect without human reports...