THE LORD OF SHABBAT- I must admit that I do not understand the fascination with the 10 Commandments as some sort of list of requirements for good living. I agree that some of them are a nice place to start for creating a civilized society: don't steal, don't lie, don't kill people, etc. However, the one that strikes me as the most strange and completely out of place as the basis of a social contract is observance of the sabbath. I was definitely amused by the Judge in Alabama who wanted to display this commandment, especially since it is not obeyed by Christians. As everyone knows, the sabbath is on Saturday, but it has been so assimilated into Christian discourse that we don't even realize it anymore. We do not follow the 10 commandments! I have no problem if we want to follow the 9 commandments, or edit them to include observance of the Lord's Day, but let's not delude ourselves. The two reasons given for sabbath observance in the OT are remembrance of the Exodus and remembrence of the last day of creation. The Exodus is only vaguely part of our spiritual mythos (and not in the way relevent to the Sabbath) and since Sunday is the first day of the week the whole creation thing sort of loses meaning.
In Christian history the idea of a Christian Sabbath (on Sunday, of course) is relatively new. As I understand it, it wasn't until the 16th century when this idea was discussed. As part of the expirementalism of the age of the Reformation, several groups began to revive the Mosaic Law in various degrees. One that stuck was the notion of a Christian sabbath, especially in America, perhaps as a result of the Puritan roots of the idea. Before that, Sunday wasn't a time of "rest" or exclusive worship. It was the day that you went to church, but after you got back there was no reason that you couldn't dig a ditch or fight a war or even watch football.
As a LDS, I observe the Sabbath because I am commanded to. I think that we have in many ways a religion that reaches back to OT archetypes of religiousity and devotion (prophecy, temple, diet, etc.) and I rejoice in this. I am not sure that the particular brand of LDS observance of a Christian sabbath has any precedent, especially not in the 10 commandments...