Two male squirrel monkeys were given gene therapy and now the normally color blind animals are able to distinguish between shades of red and green in color vision tests. In normal situations, female squirrel monkeys can see a full range of colors, but males cannot see red or green.
Is this the beginning of the end of monkey sexual discrimination? Only time will tell.
Link
There's a great deal more promise in this than accomplishment, but it certainly is wonderful to see them get this far.