In other SE 2.0 sites, I get a short header in between the StackExchange link on the left and the search box on the right. It includes account information and a link to meta (also review, chat, help). I'm not seeing this on MO - should it be there?
I've added a screenshot below. I'm definitely logged in (for example, I can see edit my account information on my user page).
It shouldn't be a browser issue, since other SE 2.0 sites work for me. The only potentially non-standard thing I did was to recover my account with a SE login and then replace it with another OpenID and delete the SE login. (Maybe that screwed it up?)