I am in an Internet Café because roadworks in front of the house damaged the phone cable.
Here's what I did:
I logged in to Google
I logged in to Stack Overflow by clicking on the Google OpenID logo
I answered a question
I logged out from SO
I logged out from Google
I opened Meta on some afterthought
A pop-up appeared saying "Welcome back Pekka! You are logged in."
I am logged in to Meta while logged out from the parent site, and from Google (I just checked).
This is not nice, as it would allow people in the Internet Café to post on Meta in my name if I have logged in and out from SO proper, wouldn't it? Unless I'd clear cookies and the history etc., but I won't remember that every time.
I may be a) overlooking some
status-bydesign aspect or b) overlooking a duplicate, in which case apologies in advance.
Update: I just explicitly logged out from Meta, performed a "Delete the last hour's personal data..." in Firefox (I don't know what it's named in english) closed the browser, opened it and was auto-logged again!
Update 2: Not even deleting all
meta.stackoverflow.comcookies manually and restarting the browser helps. I still get cheerfully greeted by name. I'm going home now, hoping that no visiting fellow Meta user will ever end up on Seat No. 6 at Tele Spass Internet Café, Cologne!