A friend of mine sent along an interesting video URL which one can watch here. It deals with the claim, which I have heard from naive politicians, that allowing immigrants into the USA helps world poverty. It is of course a production of an organization in favor of reducing immigration into the USA, but that doesn't make their argument any weaker.
In fact, immigration does help the USA, though it doesn't do anything significant to help the rest of the world. Immigration (when we do it right) brings a steady inflow of bright, energetic, "can do" types into the US population, and helps offset the demographic decline in US workers. It probably hurts the poorer nations, because we are siphoning off the very bright, energetic, "can do" types that, if they stayed home, could improve conditions in their home country.
My father, though much of his career, helped establish industrial research institutes in third world nations under World Bank and UN sponsorship. His objective was to initially staff these research institutes with foreigners, and then attract back nationals to replace the foreign scientists, until after five years or so he could leave a research institute entirely staffed by natives. What I found interesting was that even in the poorest, most backward nations he always found plenty of highly qualified, highly trained native scientists and researchers. But of course they were all in Europe or the USA, where they had gone to get their training and then stayed because there were no opportunities in their home countries.
This immigration issue is a complex one. But looking at the demographics, almost all industrialized nations face a catastrophic demographic decline in their working population over the coming decades, and nations which can replenish their pool of workers with immigrants will fare better than those who, for cultural reasons, are resistant to immigration.