This development is the combination of our increased knowledge of the CCR5-Δ32 trait and some dramatic advances in the techniques of gene therapy. This new 'zinc finger' technique is nicely described in the New York Times article: In New Way to Edit DNA, Hope for Treating Disease just a few weeks ago.
Read to the end for some amazing, and perhaps slightly troubling, possibilities of using the same techniques to alter the human germ line:
Since the germ lines of rats and zebra fish have already been altered with zinc finger scissors, “in principle there is no reason why a similar strategy could not be used to modify the human germ line,” Dr. Porteus said. The kind of disease that might be better treated in the germ line, if ethically acceptable, is cystic fibrosis, which affects many different tissues.
The disease could be corrected in unfertilized eggs, using the zinc finger technique, Dr. Porteus said. But he added, “I don’t think our society is ready for someone to propose this.”