Facebook (News - Alert) mobile has a whopping 425 million users. Given the nature of how mobile  a society we are, a lot of advertisers are missing out when it comes to reaching those people. Why? Facebook mobile is ad-free.

Well, it was ad-free.

Reach Generator, a new ad unit from Facebook, will not only take branded posts and put them on the ol’ regular desktop Facebook, but it now has the technology to stick it to mobile, as well.

The social network’s communications team summarized these ad announcements, saying, “Premium ads and sponsored stories on Facebook can now appear in two new places: on the Facebook log-out page and mobile news feed. Sponsored stories for mobile news feed increase the visibility of stories related to a business or organization to help pages share their fans’ activities.”

The ads for desktop, mobile, and logout screens will all be sold as one single package from Facebook.

UK-based analyst firm Mobile Squared recently said that Facebook can expect to generate $1.2 billion annually from mobile ads. The company has calculated that, by adding mobile to the advertising mix, Facebook will pocket around $6.50 per user annually.

However, according to Mobile Squared the revenue leap is contingent on mobile display-style ads, where reports suggest Facebook may opt to reinvent the wheel when it comes to mobile website and mobile app advertising.

Mobile Squared chief strategy analyst, Nick Lane, based his figures on data from the US and Facebook’s five biggest markets in Europe. He estimated that there are 185.3 million users of Facebook Mobile across the six markets.

Via Mobile Squared, “Google’s (News - Alert) acquisition of Admob for $750 million was a huge deal in its day, and Google expects to generate over $2 billion from mobile advertising in 2012.”

“Facebook could potentially expect to generate similar levels of revenues over a 12-month timeframe.”