“Apple Chief Financial Officer Peter Oppenheimer cited figures from market research firm The NPD Group that showed Apple doubling its U.S. notebook market share, as measured by units, to 12 percent in June from 6 percent in January. ‘We are increasingly optimistic about the potential for Mac to gain meaningful share in the back-to-school and holiday seasons, while Microsoft Vista remains unavailable until January,’ Merrill Lynch analyst Richard Farmer wrote in a note to clients on Thursday. More …