Kathryn, I was at the same rally as your correspondent (and, I gather, Byron), and had the same impression: lots of support for McCain of course but more intense enthusiasm for and interest in Palin—she was the real draw. A person in front of me held up a sign reading: “Palin supporters for McCain”.
The size of the crowd, as Byron noted below, is like nothing I’ve seen at a Republican rally. I never attended an Obama rally when he was riding high in the primaries in early spring, but I imagine this is something like what his turnout was like back then, and for a rally called on short notice on a Wednesday morning in a Virginia suburb. Extraordinary.