Does a contrast like the World State and the Reservation exist today?
In order to answer this, one would need to know what kind of contrast you mean. In the case of sheer differences in societies, there are many places in the world today that appear in stark contrast to each other. However, there is no place that is blocked off/strictly regulated like the Reservation. Certainly tribal land in America is open- one does not need a special permit to visit. In the context of American society though, many view reservations as quite similar to what Huxley presented in the novel. Whether this is true or not becomes a matter of generalization. Huxley paints a picture of Native Americans as alcoholic, unclean, superstitious people. Obviously, that is not true. So in the sense of 2 locations contrasted exactly as Huxley does in the novel, I would have to say no, that doesn't exist. But, continuing to look at reservations in America, the top five poorest areas in the country fall onto reservation boundaries. So, there is a remarkable contrast between those areas and the majority of American society.
In a larger context, one could find contrasts throughout the world. Any "modernized" society, when compared with a less-developed one, could resemble (to some extent) the World State and Reservation in the novel. There are many people who hold the same viewpoints as those in the World State, with regards to other cultures around them. The way Lenina reacts to the citizens of the Reservation echoes the way many people would react upon visiting a less-developed society. However, this does not speak for all people. I would argue that there are no places with as great a contrast today as the World State and Reservation.