By John Markoff January 15, 2008 7:37 pm January 15, 2008 7:37 pm Even more than when he’s performing on stage, Steven P. Jobs’s passion for personal computing comes through when he talks about the years he spent cajoling his designers to build what he presented today as the world’s “thinnest” computer. Along with David Pogue, the Times technology columnist, I spent a half-hour with Mr. Jobs after