I use Google as my OpenID provider. Once I log into Stackoverflow with my gmail account, can I get Google to somehow automatically log off my account? I prefer not to have my personal google account always logged in. It's not a big deal going to gmail and clicking log off, but if there is a simpler way that would be good.
Unfortunately this, by my understanding, is behaviour as designed.
The point of OpenID is that you are able to login using one set of credentials and remain logged in to multiple sites using the same account.
If you do not want accounts to be linked in this way then you need to separate them rather than have them be associated via OpenID or similar schemes.