The article gives no indication of why one would implement all this complicated CSS just to duplicate the effect of the "title" attribute. After all, tooltips are already a built-in function of every browser, and users are familiar with how they work. How is this any better than those annoying sites that re-implement scrollbars or the back button in awkward, unfamiliar ways?
I'm using css-only tooltips on various parts of my blog. Here's the code: <a href="http://blog.sachleen.com/css-only-tooltips.html" rel="nofollow">http://blog.sachleen.com/css-only-tooltips.html</a><p>It meets all of the requirements discussed in this post and uses much less CSS.