Umbilical cord stem cell research could stand much more attention by liberals, in the public eye, and in the lab.
Here's where I think an "opt-out" plan on umbilical cord donation is in order. Unless someone says something specifically about the umbilical, it goes to help further science and medical treatments. Since the umbilical has served its purpose and is no longer needed by the baby, there should be no real ethical concerns at that point.
Considering that umbilical cords and placentas are now collected for their collagen, it seems reasonable that their blood stem cells would be harvested as well.