Hizbollah does have a lot of fans in the United States. While many of the first wave of Arab immigrants to the United States were Lebanese, most of these were Christians. But in the last few decades, many more Lebanese Moslems have come to America, and many of these are Shia who admire Hizbollah for defending Lebanese Shia during the 1975-90 civil war. Hizbollah has exploited this good-will by soliciting contributions from the Shia Lebanese-American community, and trying to recruit activists there as well.
The police and military have screening systems in place to prevent terrorist infiltration, and so far, the screening seems to have worked. The recent Hizbollah chatter is a reminder that the screening actually serves a useful purpose, and that often the chatter is just chatter. But you can never be sure, because once in a while, the chatter precedes action.
Because of their "victory" over Israel this past Summer, Hizbollah now believes it is catching up with al Qaeda, at least in the bad-boy/media-star department. This has led to a lot of terrorist fanboys filling up the chat rooms, IM space and emails with pro-Hizbollah chatter. Some of that chatter has indicated that Hizbollah has been encouraging some of its sympathizers in the U.S. to join local police forces, the FBI, the armed forces, and other security agencies.