As promised, Barack Obama has answered—in detail—"the 14 top science questions facing America," according to Science Debate 2008, which sent him the questionnaire as part of its attempt to make science and technology a bigger part of the election campaign. The questions, which cover topics like stem cell research, genetics, climate change, and scientific integrity, were also sent to John McCain, who said he would respond as well.
On the topic of stem cells research, Obama says:

"Stem cell research holds the promise of improving our lives in at least three ways—by substituting normal cells for damaged cells to treat diabetes, Parkinson’s disease, spinal cord injury, heart failure and other disorders; by providing scientists with safe and convenient models of disease for drug development; and by helping to understand fundamental aspects of normal development and cell dysfunction.
For these reasons, I strongly support expanding research on stem cells. I believe that the restrictions that President Bush has placed on funding of human embryonic stem cell research have handcuffed our scientists and hindered our ability to compete with other nations. As president, I will lift the current administration’s ban on federal funding of research on embryonic stem cell lines created after August 9, 2001 through executive order, and I will ensure that all research on stem cells is conducted ethically and with rigorous oversight.
I recognize that some people object to government support of research that requires cells to be harvested from human embryos. However, hundreds of thousands of embryos stored in the U.S. in in-vitro fertilization clinics will not be used for reproductive purposes, and will eventually be destroyed. I believe that it is ethical to use these extra embryos for research that could save lives when they are freely donated for that express purpose.
I am also aware that there have been suggestions that human stem cells of various types, derived from sources other than embryos, make the use of embryonic stem cells unnecessary. I don’t agree. While adult stem cells, such as those harvested from blood or bone marrow, are already used for treatment of some diseases, they do not have the versatility of embryonic stem cells and cannot replace them. Recent discoveries indicate that adult skin cells can be reprogrammed to behave like stem cells; these are exciting findings that might in the future lead to an alternate source of highly versatile stem cells. However, embryonic stem cells remain the 'gold standard,' and studies of all types of stem cells should continue in parallel for the foreseeable future. ..."

Those who keep tabs on the relationship between science and religion in politics will also be particularly interested in Obama's answer to the question on scientific integrity:

"Scientific and technological information is of growing importance to a range of issues. I believe such information must be expert and uncolored by ideology.
I will restore the basic principle that government decisions should be based on the best- available, scientifically-valid evidence and not on the ideological predispositions of agency officials or political appointees. More broadly, I am committed to creating a transparent and connected democracy, using cutting-edge technologies to provide a new level of transparency, accountability, and participation for America’s citizens. Policies must be determined using a process that builds on the long tradition of open debate that has characterized progress in science, including review by individuals who might bring new information or contrasting views."