The order of these sections now changes depending on the search keyword. For example the Do section appears first on the "Buy Car" result page - as this is clearly a transactional search. Currently the "Buy Car" results page enables user's to quickly search AutoTrader to buy a car.
Other queries are navigational in nature. "Facebook", for example, is currently one of the top 10 searches that users enter to Find the social networking site facebook.com.