Facebook may be seeing positive cashflow and excellent rates of growth, but it’s also dismally unprofitable considering the size of its user base. That gives it the impetus for an all-out mobile payments push. It’s already primed for success: with about 100 million active users in the U.S., it already reaches about half the population between ages 15 and 64, and it already has those users accustomed to using their Facebook credentials all over the Web. Its Facebook Connect portable gateway technology has already been adopted by 80,000 websites, says Facebook, including giants like MySpace and YouTube.

But other players are trying to wrest the payments market from Facebook’s sleepy grasp. American Express just spent $300 million buying online payments startup Revolution Money Inc., a pet project of AOL founder Steve Case. Nokia spent $70 million on its Obopay stake, and venture-backed Boku acquired two smaller competitors this summer for an undisclosed sum.

via BNET.