Somehow I'm the last person to hear about this. A previously uncontacted tribe sighted along the Brazilian-Peruvian border in the most remote part of the Amazon. A plane sighted them and by the time it returned to take pictures they had painted themselves red and were shooting (or at least threatening to) at the plane as it passed.
Oh, and besides the loggers who are just straight out shooting them, the other major threat to them are missionaries who go trying to "save" them and end up exposing them to diseases that wipe out half their population in less than two years. Argh!