There's a real array of answers here. My best suggestion would be to start the conversation pertaining to this topic with some specific, open-ended questions.
"You know, recently our son has come home talking about some classroom discussions regarding other kids behavior. Most specifically, he mentioned Dalton and Victoria being discussed for acting out. He's concerned that if he makes a mistake, he might get called out in front of the class. Could you help me understand what happens during those times, and why these incidents are brought to the attention of the class?"
Some teachers have a 'class meeting' type of gathering each day where kids can air grievances with each other while feeling supported by the teacher. (as well as practicing their "I" statements, such as "I didn't like when Suzy cut in front of me at the fountain", etc.) While I personally wouldn't have a group discussion like this with my age group (preschoolers), some teachers have been taught to handle some classroom conflicts this way. That said, I would only find it appropriate if what Dalton or Victoria did was affecting the children directly and there was some child-initiated problem-solving happening around this.
Being open and asking the teacher, while putting it in the context of "this is confusing for my kid" may give her pause as to how she is discussing this with the class. I personally wouldn't hesitate to draw a small comparison: "You know, at home we make it a point only to discuss a person's negative behavior with that person alone, or just with the people involved in a given situation, because kids do make mistakes, so calling the attention of the entire classroom to it is pretty different. How could I explain this so that he understands, because it's easy to see how he thinks that Dalton and Victoria are being called out in front of the class?" This puts the ball in the teacher's court, and you might be surprised by what you hear. Perhaps there is a philosophy behind it, perhaps she does want to shame them. Perhaps Dalton's behavior is emerging as a bigger issue in the classroom and she wants to find out what the larger impact is, esp. during recess or lunchtimes when she might not be with the class and the monitors might not catch/communicate what's happening.
While I think all of this is very unfortunate, it is another opportunity for us to find out about what the teacher is thinking and if you approach this as an opportunity to support your son (and if you can keep that attitude during the conference, which should help both your and the teacher's feelings NOT escalate), you could learn a lot. I agree that the whole thing kind of stinks, but I don't know what that teacher carries with her, what her previous teaching experiences have been, or even what sort of parenting and teachers she had as a younger person. All of these factors can contribute to how this teacher manages her classroom in the present day.
Lastly, I'd strongly recommend reading "The Essential Conversation: What Parents and Teachers Can Learn from Each Other" by Sara Lawrence-Lightfoot. This book has been insightful for me as both a preschool teacher and a mother. So much of what we experience before/during/after our conferences is perceived through the prism of our past experiences of our own, for teacher and parents both. You can do this, L.. If the conference goes horribly, ask for a meeting with both the counselor and the principal. If it goes well, you might consider waiting a bit and seeing if the 'classroom call-outs' continue, or if the teacher gets the message that this is confusing for the kids. My best to you on your conference.
(If necessary, as someone else had suggested, this is a great subject to broach with the guidance counselor, because there is the danger of 'labelling' of kid like Dalton and Victoria. We don't know what's behind either of their behaviors, either, but I expect that there are always 'below the surface' issues which are like the bottom of the iceberg-- the behaviors are only the tip of that iceberg. )
