> does HN store IP addresses for the purposes of identifying user accounts?
They use cookies assuming you are logged in. I wish they do store IPs in order to prevent password brute-forcing attacks.
> I wonder if HN was hacked if "anonymous" posts would be linked back to actual people even though no email address is on the account.
You should be more concerned about your email account being linked to your HN username, fortunately you don't have to provide your email here.
> OK so maybe HN should be clear that anonymity is not likely if HN is hacked. HN sort of presents as being a "safe" place to post anonymously but it's an illusion.
It's pseudonymous forum, if you wish to be anon - head over to 4chan instead.