While I understand (but disagree with) the rationale provided to adding an arbitration clause in the new TOS update, particularly in this thread, one thing I must take umbrage with even given that rationale (avoiding spurious lawsuits) is this:
You agree that, notwithstanding anything in the foregoing, any arbitration proceeding between you and us will be conducted in New York, NY, USA, that the language of the arbitration shall be in English, and that all arbitration proceedings shall be considered confidential in nature.
The rest of the arbitration stuff I could probably stomach, but requiring confidentiality is how arbitration is most effectively misused by corporations: when something bad does happen, the consumers who discover it are forced into arbitration and forced to not reveal the terms of the settlement (or even of the issue that caused them to go into arbitration in the first place, oftentimes, if they hadn't already shared it publicly).
I would suggest to the folks at StackExchange corporate, that if you're truly of good intent here, that you get your legal folks to either remove the confidentiality entirely, or significantly amend it to protect our rights to disclose any injury or tort publicly. If you're just avoiding spurious litigation, this shouldn't have any impact on you - your arbitration record will be clean. But if StackExchange does do something bad in the future, such as misuse our private data, it's imperative that we have the right to communicate that injury to the world at large so we can protect ourselves.