In fact, Google’s search engine, as well as Microsoft’s (Bing), both ignore the Do Not Track header even though both companies helped implement this feature into their web browsers. Yahoo Search also ignored Do Not Track requests. Some websites will politely inform you, however, of the fact that your Do Not Track request has been ignored, and explain that this has been done in order to preserve their advertising revenue. But not all websites, by a long shot, do this.
The revalations come as Congress and European legislators consider to tighten privacy standards amidth massive advertiser lobbying. "Do not track" received strong support from the European Commission.