Yes, Obama is doing the right thing.
I think Eric Etheridge needn't be so worried about "science" taking over (great link, Alexis). We will always have political intrusion into science; at no point will the purely "scientific" view prevail, simply because there is no such thing. There are scientists, but they are all people will personal views. All scientists bring their moral and ethical views to the mix of what they present, how they present it, etc. They can't avoid it as long as they are human.
What all good scientists also try to do, earnestly, is separate their wishes from the facts. So you can propose a theory, but a bad scientist cherry-picks data to support his theory, while a good one does everything he can think of to destroy it. Read anything by Richard P. Feynman, Physics Nobel Laureate, for a perfect illustration. His "Surely You're Joking, Mr Feynman!" is a delightful read-- and tackles these moral issues with regards to the Manhattan Project.
What I see too often on the other side of the equation is people who don't understand a nit about science-- take Sarah Palin's incomprehension over funding for fruit flies-- who vigorously oppose something based purely on their feelings. Diana DeGette discusses the astounding ignorance of her fellow congresspeople in her book, Sex, Science and Stem Cells. Well, my feelings are as valid as yours. If you "feel" life begins at conception, you "feel" as if stem cell research is wrong-- but people "feel" many things that simply don't hold up under examination.
Defining the moment life begins is impossible from a scientific view. The cells are already alive. I lose an egg a month, and I'm not crying bitter tears over these potential lost children. To do my duty to them, I should be pregnant all the time! But then... all those eggs in waiting wouldn't have a chance. Oh, the loss! Never mind, here comes one now, down the fallopian tube. Let's pretend I finally intercede on its behalf, and this one gets fertilized. In the normal course, I'd have a 50% chance of a miscarriage. That's right; 50/50 that precious life is lost before I even have a clue it's there. The pregnancy just doesn't take and it's completely natural.
In this natural early miscarriage, my "baby" is about the size of the head of a pin. A fly is about a million times more complex, but I swat the fly and don't think a thing about it. But humanity is so precious in comparison! I hear the objectors cry. Humanity has a soul!
You're quite right that, from a religious view, this is very important to determine. Philosophers have struggled over this for millennia, because we need to know for purposes of civilization. The results are all over the map. For the Catholics, St. Thomas Aquinas felt that a certain amount of complexity was necessary for a human body to support a soul. A soul couldn't go into the dot; the potential child had to have enough brain and development, in his view. He put the figure at 3 months after conception. For the early Jews, the time was 3 months after birth. I suppose that was because the infant mortality rate was so high. If your baby died shortly after birth, it was buried nameless in a separate place in the cemetery. It didn't undergo the early rituals because it had failed to live the minimal required time to get named and recognized by the community. This isn't to say the parents didn't mourn; I'm sure they did, but it was recognized under the "things happen" clause.
All societies do this-- attempt to define what works for them. There is no "right" answer here. What I look for personally is, "Who is harmed by it?" I fall on the side of the mother who must carry the child to term, and support it afterwards. The pinprick that is an unborn life cannot suffer in any way; it doesn't even have nerves, let alone self-awareness. On the other hand, my pregnant mother is fully self-aware. She may be aware that she can't reasonably support a child, feed it, give it the care and attention it needs. Forcing this woman to carry to term is a cruelty to her and to her unborn child.
In a world where the living population will soon outnumber all the people who have ever lived in history, I don't think we need to worry unduly about all these unlived lives. In my view, 50% of these embryonic cells would "die" anyway, in Nature's course. If you're talking about the output of fertility clinics, these unused embryos are being destroyed anyway. Potential does not equal a child. If you want to hang a murder charge on anyone (which I don't think you should), pin it on these selfish parents who, in a world of millions of needy children, choose to jump through technological hoops to make their own. The clinics make "extras" knowing they will never use all of them, and that not all will take. They are making embryos knowing they will kill some. I personally think the whole practice selfish and wasteful, but again, there is no "right" view here. It's all a matter of opinion.
A surer guide to me is looking at the issue in terms of who is suffering more-- this frozen dot, or Michael J. Fox. I'm sorry, I'm going to come out in favor of the thinking, self-aware person who's already here.
And please don't jump to conclusion that I don't value life, simply because this is my view on stem cell research. I do value life. I suppose I'm more in line with Aquinas in thinking that a certain amount of complexity is required-- the embryo has to get to a certain stage before I'm going to grant it protection. But I'm also in favor of a good life, a life that means the mother and the child can pursue their lives with a reasonable chance of happiness. To do otherwise, to force people into a lifelong situation of impoverishment because that little bitty dot had precedence, I think is monstrous.