From Afaransis, we learn that not a new species, but a whole new GENUS of monkeys was discovered in Africa, the first such find in 83 years!
USA Today has a short write-up, while Science Daily has a longer, more informative one.
Lindsay makes a couple of important points about what it means to "discover" a new species.
This is quite exciting really, as Africa was pretty well researched over the past century or two.
On the other hand, a friend of mine was one of the first Western scientists to enter Laos after decades of isolation. After almost dying of malaria, and almost dying by being shot at by poachers, he came back and reported several dozens of species, and several genera not known to Western science before. Most of those were amphibians and reptiles, though, as that is his specialty. Several years later, he is STILL sifting through his collection and trying to classify everything he brought home with him.
Update: Good points by Josh Rosenau - puts it nicely in perspective.