Although I'm familiar with Thawte, I hadn't heard of its "Web of Trust" prior to this article. However, there's a popular browser add-on with the same name, so I thought I should point that out to avoid any confusion, especially since both products are related to Internet security in some way.
Web of Trust is also the name of a Firefox and Internet Explorer plug-in from a company called WOT Services Ltd. (until recently known as Against Intuition Inc.). It helps protect users from harmful Web sites and puts safety rating badges in search results on Google, Bing, Yahoo!, and other search engines, similar to McAfee SiteAdvisor and Symantec's Norton Safe Web (although in my experience, WOT is much more effective). This completely unrelated Web of Trust is not being killed off.
I hope that clears up any potential confusion.