"This is how Jesus was born," the poster states. "Joseph and Mary participated in the Census."

The Rev. Miguel Rivera, chairman of the National Coalition of Latino Clergy and Christian Leaders, says invoking the name of Jesus to promote the 2010 Census is "blasphemous" and "violates the concept of separation of church and state." Using the name of Jesus for "a political and secular intention, it is definitely an assault against our Christian faith," Rivera says.

I don't see how that poster is "blasphemous".

...thousands of posters that depict the arrival of Joseph and a pregnant Mary in Bethlehem more than 2,000 years ago.

... and, of course, the Incarnation throws a wrench in the strictest interpretations of the Commandment against graven images, since God has taken on human flesh: i.e. "depicted Himself."

because with the incarnation God actually has an image to depict, which he did not before.

(though of course religious imagery and statuary was still permissible even before that if we look at the cherubim in the adytum)

Yeah, I get that, but He still never said we could do it. The problem wasn't that we didn't have a live model. We were told not to do it.

Do not make idols or set up an image or a sacred stone for yourselves, and do not place a carved stone in your land to bow down before it. I am the LORD your God. (Leviticus 26:1)

I am not of the opinion that through the Gospel all the arts should be banished and driven away, as some zealots want to make us believe; but I wish to see them all, especially music, in the service of Him Who gave and created them... I have myself heard those who oppose pictures, read from my German Bible. … But this contains many pictures of God, of the angels, of men, and of animals, especially in the Revelation of St. John, in the books of Moses, and in the book of Joshua. We therefore kindly beg these fanatics to permit us also to paint these pictures on the wall that they may be remembered and better understood, inasmuch as they can harm as little on the walls as in books. Would to God that I could persuade those who can afford it to paint the whole Bible on their houses, inside and outside, so that all might see; this would indeed be a Christian work. For I am convinced that it is God’s will that we should hear and learn what He has done, especially what Christ suffered. But when I hear these things and meditate upon them, I find it impossible not to picture them in my heart. Whether I want to or not, when I hear, of Christ, a human form hanging upon a cross rises up in my heart: just as I see my natural face reflected when I look into water. Now if it is not sinful for me to have Christ’s picture in my heart, why should it be sinful to have it before my eyes? (Ref; Martin Luther's Preface for Chorgesangbuch by Johann Walter, 1524)

... and, of course, the Incarnation throws a wrench in the strictest interpretations of the Commandment against graven images, since God has taken on human flesh: i.e. "depicted Himself."