I basically copying my answer from https://genealogy.meta.stackexchange.com/a/95/35 as the questions are about the same thing...
Based on some comments I've read and thinking about it more I'm going to say that we should not have a policy any people or what information can and can not be said. This should be left up the the posters discretion.
My main reason for this is that each country has different items that are considered sensitive. Having a massive list of whats not aloud for each country would be unwieldily and most people wouldn't look through it before posting anyway. The person posting the question from whatever country should know best.
I don't think we can outright ban personal information at all from the site either as it would make asking questions exceedingly difficult if not impossible. When viewing a question and seeing a SSN number I'm going to assume the person posting knows what he or she is doing and that SSN is for a deceased individual where the SSN in already listed publicly. If its obvious that the person is still alive or recently deceased a comment regarding the wrongness and the potential consequences of identity theft can be made.
If I see a Tax ID from other countries I have no idea if its sensitive or not, same with any other information being posted.
My vote is not to have any policy other than "Be careful what you post" same as any other forum, blog, social site, etc. on the internet.