Wow. First wanted to say how horrible this is. I am so sorry your child is being physically assaulted and the teacher 'obviously' doesn't have a clue (either that it's happening or what to do).
First things, if you have not done already - make sure there is written documentation of each incident, the office needs to know about it, and a meeting probably needs to happen with the school and you as to concrete steps to deal with the classroom wide issue. I personally would probably call the parents of the child who is doing the one-on-one fighting, that has helped us in the past with name calling from one child.
I know some folks would disagree with contacting a kid's parents, but in my opinion most parents would want to know.
Yes, it seems clear the teacher thinks your ds is part of the problem, and in some ways that can be the case, however it doesn't excuse kids from going too far in verbal or physical bullying.
I think you have probably checked out this book, iirc:
http://www.amazon.com/Unwritten-Rules-Friendship-Strategies-Friends/dp/0316917303(I seem to recall you were interested in a previous thread on social skills books, courses, etc.) This book has some info on the child who is 'asking for trouble' and some other variations on this. Might be a place to start, anyway, if you have not checked it out.
I hang around the bus stop within earshot of my ds most of the time, especially back when he was really having issues fitting in. I found out that when confronted by other kids he would fall into a fairly rude sounding, condescending tone. During one verbal interchange where one kid said something like 'pokemon game is g*y', and my ds was firing off a pretty snotty sounding response, I stepped in and corrected everyone. To the boys being grossly mean, I said I heard what you said, that is really rude and mean, and to ds, you need to take a nicer tone! Everyone needs to be nicer to each other! I am not entirely sure, but I think seeing me correct my own ds about his tone of voice/attitude might have broken down some barrier, they are at least on adequate speaking terms now. (There were other factors too such as allowing ds to get some cool handheld video game in order to fit in / have something to do with this brain and hands )
Have you had any luck finding a social skills course for him? the more I reflect on ds' progress since taking a course this summer, the more impressed I am with it. Perhaps some is due to age, I think he has a greater understanding of when to stop going down a non-productive path (negative attention) and rethink his approach to people. Something like this could help your ds in projecting a more likable, confident self. (Part of that is of course the idea of liking one's self...is he doing ok with that?)
Last comment...I have always told my ds he is allowed to defend himself, and if he gets in a bunch of trouble, to leave it to me to sort out - I would rather go this route personally, than find out how far he can be pushed.
