President Obama lifted the ban on public funding for embryonic stem cell research. The embryos used for this type of research are the "leftovers" embryos from the process of in vitro fertilization. The hierarchical magisterium already condemns the process of in vitro fertilization.
This entire process is a difficult situation filled with shades of sketchy morality and the dangers of human farming. In one sense, since the embryos are already there, I would lean towards making use of them towards research. These embryos will never be brought to term and be born (and the Vatican would view it as sinful to do so). On the other hand, there is the danger of mothers being paid to be embryo producers if there would be shortage of in vitro embryos and there should be legislation in place to prevent such embryos from being used.
Ideally, mothers would not opt for in vitro fertilization, but would adopt. Any one reading the newspapers these days can see that the foster care system is in shambles and there is a great need for parents to adopt. There is too much stress over having your own genetic children.
A Faithful Catholic