Paul Simon was supposed to perform "Bridge Over Troubled Water" at the World Trade Center site today. He did "Sound of Silence" instead, not that we're complaining: NPR's Margot Adler called it "perhaps the most moving moment of the ceremony," and we don't doubt it. (If nothing else, the lyrics to "Sound of Silence" are much better, and arguably more appropriate, at least in the ways that their meanings have changed between 1964 and 2001, and between 2001 and now.)
Simon, you might remember, was the first musical guest on Saturday Night Live after 9/11, performing "The Boxer" to a crowd of emergency workers; that was a different kind of a performance (and a very different kind of, uhm, "national moment"—check out that flag!), but there's still something oddly moving about Paul Simon, looking like an outer-borough politician in his suit and 9/11 baseball cap, brought to tears ten years later.