from what I've seen and read, it's bits and pieces of all of that. it's definitely not a monolithic block yet. I remember seeing a video last September from that march in DC. the reporter making the vid hooked up with the Arizona Minutemen contingent for the march, and the AMs were visibly distressed (and at least somewhat disgusted) at some of the outright nutbaggery taking place around them.
while I do laugh at most of what's considered tea bag political beliefs, I find the anti-corporate message most of them seem to espouse quite refreshing coming from conservatives...and you know what? even the racists and birther retards are at least getting off of their asses and getting involved in the process; gotta give 'em props for that, even if I disagree vehemently with their goals.