Incidentally, the Solemnity of Mary, Mother of God, will not be a Holy Day of Obligation in 2007- it will fall on a Monday, and the obligation to attend Mass will be dispensed with.
Yes, today is a holy day of obligation in the United States, not necessarily elsewhere. But today is NOT the Solemnity of Mary, Mother of God, as that is 1 January. Today is the solemnity of the Immaculate Conception.
Check with your local Episcopal Conference to make sure they have not suppressed the obligation. If you are in the USA, today is a holyday of obligation.
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