http://www.dogpile.com/ http://www.dogpile.com/ doesn't make sense on two levels to me. First, they republish results from a bunch of major search engines, inc

http://www.dogpile.com/ http://www.dogpile.com/ doesn't make sense on two levels to me. First, they republish results from a bunch of major search engines, including Google, and they are all okay with that? My understanding was that Google doesn't generally allow something like this. Second, how are they combining results? If they have some objective function that can rank results given a keyword, then what are they using Google, Ask, and friends for? Free web crawler + web spam filter?