I went to one of these events. About 60 adults and maybe 40 kids. Also a few union memebers were there to "counter protest" the Tea Partiers.
The TP people surrounded a politican and asked questions. None of them had signs. All of the questions were related to healthcare. The union people stood by themselves, some were mingled with the crowd.
One of the union people standing outside the group wanted to ask a question but couldn't get the politican's attention, and a Tea Party person pointed this out to the politican so that the union person could ask her question.
My estimate: There was zero confrontation.
BTW this was in an open park, no metal detectors or body scanners. They didn't even ask me to show ID. I just walked up. No one got killed.