I didn't notice it at first, but thanks to some awfully observant folks (my wife included), the U.S. National Anthem was not sung at the Winter Classic. I know, I just saw the replay on Universal HD.
Instead of the 3 and a half minute anthem, the League instead decided for the one minute 30 second "God Bless America" sung by an Irish Tenor (if you can figure that one out, you deserve a medal). But looking back, the Irish Tenor spent a good minute to two minutes saluting the troops. With out the banter, the League could have fit the Star Spangled Banner in after all.
I also found it weird that the League normally doesn't do the Canadian Anthem when two American teams are playing, which last time I checked Buffalo and Pittsburgh were both still below the Northern border. I thought it was classy that the League did do the Canadian National Anthem. But, then to stiff the U.S.?