I followed a link from here and tried to vote. SE told me to log in. When I did, SE told me it will create a new account.
That is despite the OpenID matching the one used and listed here.
If it wasn't entirely clear, when you click through the last link above to the SE account list, and hover over the English.SE card, it shows http://english.stackexchange.com/users/5614 (5614)
A quote from balpha:
You used a different google account to log in to english.SE.
It is so. I keep thinking the fact that I have logged on to some SE sites would transfer to other SE sites, regardless of which OpenID I have going at the time. This is very confusing and annoying, that the Global Login™ is not really smooth.