With the hackers not changing the passwords to lock users out of their accounts and with only stealing stuff from one character, it really does look like a session hack and not an account hack. Or maybe it is not a hack at all. Maybe there is a bug that is causing all your items to just disappear. So, when you log out and it saves your character it fails to save your inventory for some reason. Both of which point to Blizzard and not the user.
No its a session hack, that's the thing. They take over your session for the character you're currently playing, all they need is your battlenet id. I don't know where the authenticator comes into play in this whole scheme of things but it seems to prevent it from happening so I have one for the phone.
It's blizzard's error, plain and simple. They're pushing back real hard on it from a PR standpoint, but I bet they're frantically trying to figure out how to fix it on the backend so they can say "this never happened".
I realize it's just a game, but people have a right to get worked up about it when it's pretty much a MMORPG, gear grinding and everything included.