Yes, the irony is huge... Plus, when Romney was gov. of Mas. he passed a almost identical law. Oh, but first thing he will do as pres. is scrap it. Republicans, don't you love them. :D
I am not in any way defending Governor Romney's actions in Mass. but, what you and almost everyone else I've heard make this argument failes to realize is, state law and federal law are two completely different things. It is in fact within the power of the state to legislate things like healthcare if the people so desire. It is NOT (constitutionally) within the federal government's power to do the same. There is are many reasons we have a constitution but one of the main ones is to reserve such powers for the states and keep it out of the hands of the federal government.
Now. Since that line has not just been stepped over, but rather lept across with gusto, there is at this point nothing, from a precedent standpoint, to stop the federal government from doing whatever the hell they want. To men, that is not a very encouraging prospect.