In February Facebook announced that the company had surpassed the 100 million user milestone in terms of access on mobile devices. Yesterday, while speaking at the MobileBeat conference, Erick Tseng of Facebook announced that the company had surpassed 150 million users on mobile devices. While not growing as quickly as Facebook’s primary destination site, it’s an impressive statistic and highlights the shift toward mobile devices.

Most surprising, although not unexpected, was that Tseng stated that the company is moving towards a “platform strategy”, continuing that, “we’re going away from a one-off app strategy”. Given that Tseng helped build Android, there’s no doubt that the company could work on building their own mobile operating system, although it’s kind of late in the game at this point. Whether or not the company will provide developers with distribution through their existing mobile applications or instead focus on the web is unknown.

Given that HTML 5 is gaining traction, there’s a good chance that the company will begin investing more heavily in the mobile version of the site as accessed through smart phones. Those users will then be able to install Facebook applications to their accounts, within the website. This is all speculation however, but given Facebook’s ongoing push toward mobile, we should expect a lot of developments in this space over the coming months and years.

Perhaps at the next f8 event Facebook will officially announce the Facebook Mobile Platform?