Although the article has a little sensationalistic scent, it's essentially correct.
I have just some comments and corrections:
1) R$ 7.50 equals more or less US$ 4,00. Globe and Mail is a canadian newspaper, so the $6 should be canadian dollars.
2) This place as the article says isn't exactly at Rio de Janeiro. It's the suburbs, cities that surround Rio de Janeiro, which are really plagued by violence but also have a number of Non-Governamental Associations that fight against poverty and violence. G&M could make an article about these associations as a counterpoint.
3) I can say, as brazilian and as someone that frequently went to Rio both to business and leisure, that the violence problem in Rio is normally exagerated - remember, the business of the newspapers is to sell newspapers, so they overtone the violence. Actually, the most violent place in Brazil is nearby Vitoria, capital of Espirito Santo state. Anyway, like any other place in the world, if you're a sucker there you'll have no chance.
4) The phenomenon of gangs is not new and isn't restrict to Brazil. Just rent West Side Story to see essentially the same thing happening in the U.S. The film just adds choreography and (unforgettable) music by Leonard Bernstein and Stephen Sondheim.
5) To the people that ask if these boys don't have any better thing to do, the answer is no. Duque de Caxias is 80 km from the downtown, and there is no facilities like decent mass transportation from and to there (buses and trains). So these boys end staying there and doing this sort of things. These people have been deserted from the government since a long time. The problem is a social one, and I don't think that the "goods of global economy" (do they exist to South America?) will reach this place some day.