You ought to read comments before replying to them. I clearly said that only those four are using jQuery, and that the remaining sixteen do not. I checked all of them by hand before stating this, except for Wikipedia because it is common knowledge that MediaWiki uses jQuery.

Also, your idea below about sniffing for $ is a bit embarrassing. Firefox, Chrome, etc. have come with $ for many years as an ID or query selector, and it has nothing to do with jQuery. Prototype and MooTools also provide $, and probably a dozen or more similar libraries you haven't heard of.