Almost one in five new Facebook fans came from mobile devices in August, an increase of 280% in four months, according to a new research report. PageLever looked at more than 500 Facebook Pages with 100,000 or more Facebook fans and found only 5% of new fans came from mobile in May, but that number jumped to 19% in August. It’s unclear exactly what propelled the spike in activity. Facebook had 543 million mobile users in June and reported that the figure had passed 600 million in early October. Read the full story at Mashable.