Three stories I've come across recently:
Ecuador - Ecuador has eliminated the transmission of river blindness. This story was posted on Twitter by Nicholas Kristof: "Carter Center reports Ecuador has eliminated River Blindness transmission. Congrats to all on a great achievement!" More information on the Carter Center website.
Haiti - Dr. Paul Farmer's Testimony to the US Senate Committee on Foreign Relations strikes a hopeful tone and provides pointers for how to make the best of the reconstruction efforts underway in Haiti.
DR Congo - John Prendergast argues that the conflict in the Congo could finally be turning a corner in Foreign Policy Magazine.