According to a post on Facebook's blog, the company has tripled its audience on mobile devices to 15 million over the past year, MediaPost reports. The number includes the m.facebook.com mobile WAP site as well as the various native applications available for different handsets.

"[This is] a big milestone," said Julie Ask, a JupiterResearch analyst who covers the wireless space, in a blog post. "I think this number will only continue to grow and everyone in the ecosystem will benefit."

The report said that Facebook, and social networking in general, will benefit from the trend toward cell phones with larger screens and full keyboards. "The more users post to the mobile site, the more often others will check in for responses, and that 'virtuous circle' will help social networking expand on mobile devices," the report said.