Barack Obama left his 2.6 million fans on Twitter, the social networking website, bemused, disappointed and mildly irritated by admitting on Monday that he had never used the service himself. "Let me say that I have never used Twitter," he told students in Shanghai. "I noticed that young people are very busy with these electronics. My thumbs are too clumsy to type in things on the phone." During his election campaign, Mr Obama portrayed himself as "connected" to the people through Twitter and his ever-present blackberry phone. Some of his more understanding fans asked if it was any real surprise...