After tackling evolution yesterday, why not stem cell research today? :) Something that is usually overlooked in the debate is the difference between embryonic stem cells and adult stem cells, as explained by Dr. David A. Prentice:

I am in favor of stem cell research. In fact, I don't know anyone who is opposed. If this sounds startling or puzzling, it's because many people don't know that they need to look for an adjective that should always be present in a discussion of stem cell research. Without an adjective defining the source of the stem cells, the term is misleading and spreads confusion.

There are many sources of stem cells, but the two most often discussed are embryonic stem cells and adult stem cells. Embryonic stem cells come from early embryos within the first few days of life. Obtaining them requires the breaking apart of the embryo , which necessarily results in death. By contrast, adult stem cells can be found in virtually all tissues of the body from birth onward (as well as in umbilical cord blood and placenta) and harvesting of these cells does not harm the individual from whom they are obtained.

Despite the hype surrounding them, embryonic stem cells actually have little to offer for treatment of disease. Their supposed advantages -unlimited growth and potential for forming all tissues- are hindrances when it comes to transplants to repair damaged tissue. When transplanted into experimental animals, these cells generally continue this untamed behavior, with a tendency to form tumors or various unwanted tissues. (Dr. David A. Prentice, The Real Promise of Stem Cell Research)

It seems as though many people critiquing the US veto aren't aware of this distinction. Adult stem cell research is still legal, kills no one, and is ongoing today. For more on why people reject embryonic stem cell research, see "Are you against stem cell research" (PDF) which asks the question "Wouldn’t you agree it is wrong to kill one human being to do research on her body to help someone else?"