I always wondered when content spammers would begin taking advantage of some of the "Smart Searching" functions, provided by the search engines. I have been tracking a package of mine and decided to use Google. So I entered in a UPS tracking number, for example, 1Z W64 W91 67 4523 244 6 and using Google's Search By Number feature, it brought me the following results.
But it is perfectly ethical, since they are not cloaking, the cache page is exactly like the landing page. Don't worry, nothing is currently being shown on that landing page besides for tons of numbers and a link to the site.
I started a forum thread at Cre8asite Forums.