If one wants commercial results on say "shipping" one would logically type "shipping services", if one wants information on how to ship one would type something like "shipping proceedures".
Not everything is that simple. Let's say you are a student researching a well known book on widgets. What would the average user type in? 'book on widgets' is my guess. So both results of sites selling the book and information on the book would show up.
The same goes for other information sources. If you are researching a widget would you want to buy the widget or learn of certain information regarding it? The average user is lazy and don't know what to expect from search engines. They think that once they type something in it should show up #1 in the results on exactly what they want. With a tool like this, the user won't have to go through pages and pages of results searching for just one listing of information or shopping material.
This is very useful for those 'lazy' users. Which is probably a pretty large majority.