Today Facebook revealed that it now has more than 1.49 billion monthly active users, 655 million of whom only access Facebook via a mobile device. That means 44 percent of Facebook’s active user base literally never touches the service via desktop. The trend isn’t surprising — it’s been headed in this direction for years — but we’re certainly nearing a turning point for the world’s largest social network, a company that once alarmed the SEC over its risky mobile numbers pre-IPO.