The Arizona law does not target individuals who broke the law at all, it targets those who suspected of being there illegally. How on earth do you determine if someone is there illegally if it weren't for some criteria based on what an illegal immigrant "looks like"? i.e, not white
So while I don't think it's the U.S' responsibility to solve the world's problems (though the U.S government seems very selective on where it decides to stick its nose), they are responsible for facilitating the use of illegal labor through poorly regulated immigration laws.
How do you determine if someone is here illegally? Simple. Driver's License please? Oh you don't have that, Green Card please? Oh you don't have that. State or federally issued ID card? Oh you don't have that... and on ad nauseum.
I think they (law enforcement) will be taking in the totality of the circumstances when asking/determining whether someone is here legally or illegally. And yes, in AZ anyway, I think they're perfectly justified in profiling, as most of the illegal immigrants there are Mexican. I doubt they've got a rush of Swedish illegals flying in from Stockholm and I doubt they've got swaths of Cambodians floating in from across the Pacific.