http://www.macworld.com/article/154266/2010/09/html5_lawsuit.html
claiming that the company is abusing HTML5’s local storage feature, using it to store a tracking “cookie” that can’t be deleted when you delete your browser’s cookies.
they don’t go away when you delete your cookies. And browser fingerprints—an emerging tracking method.
http://www.wired.com/threatlevel/2010/09/html5-safari-exploit/
Lawsuit Targets Mobile Advertiser Over Sneaky HTML5 Pseudo-Cookies.