HTTPS on Stack Overflow: The End of a Long Road
Stack Exchange is no longer available from my workplace due to this change.  We have a strict no-posting-code-fragments policy, and SE was viewed as too risky to allow without some restriction in place to make it read only.  Before HTTPS, the IT department had worked out such a read-only restriction by blocking the SE login with firewall rules.  But with HTTPS that kludge is no longer possible, so the site is blocked.