No way.. marriage is a sanctified relationship between a man and a woman under the eyes of God. It has always been defined that way, and it should stay that way.
Now, if you replace the word "marriage" with "civil union" with all the rights and responsibilities that go with it, I wouldn't have a problem with it.
As far as this case goes, Seagoon, read the article. The couple (two women) decided they wanted a kid. The one lady's brother impregnated the dead lady, and the couple had a kid. But it really is the couple's child.
If a married man and woman decided they wanted a child, but the man was sterile so someone else impregnated his wife, and then the wife died in a car accident... you would still consider that child to be the man's child, even though it isn't really biologically his, right?
I don't see it as being any different.