Diversity immigrant visa - the "green card lottery"

I didn't know such visas existed until I heard about them in an interesting podcast form This American Life.

The lottery makes available 50,000 permanent resident visas annually to natives of countries deemed to have low rates of immigration to the United States... They must satisfy general immigration requirements, such as means of support, no criminal background, and good health... Those born in any territory that has sent more than 50,000 immigrants to the United States in the previous five years are not eligible to receive a diversity visa...

[T]here have been arguments by longtime temporary legal residents in the United States against the fairness of the DV program. A situation where high skilled (H-1B and L-1 visas) workers and taxpayers remain on temporary visas in the US for years (in some cases, more than a decade) with no clear path to becoming permanent residents while 50,000 random people are picked around the world and handed permanent resident status questions the fairness of the US immigration system.