The New York Times has an excellent Op-Ed piece Migration hurts the Homeland by Paul Collier a Professor of Economics at Oxford. He points out how immigration from poor countries to rich countries by the elite damages the former. Mark Zuckerberg, founder of Facebook, has recently been arguing on liberal political grounds for increased immigration to the USA. But, actually his arguments are just self serving, since companies such as his, benefit from the brain drain to the USA. The rich and powerful are insatiable.
On related issues, Vinoth Ramachandra has a provocative blog post Robbing the Poor, that points out Australia's double standards.