I think they can make a ton of money there. First, allow devs to sell apps just like on Xbox Live and phone app stores. Secondly, require as policy that any program bound by the SDK license will only use Facebook's payment system to charge users for anything. Open this payment system up to people who need to collect small payments unrelated to Facebook; many of their customers will already have a Facebook account--it's like Facebook Connect but more useful.

Except that the primary users of FB are twenty somethings who generally aren't that willing to spend money on stuff online.

Besides the biggest customer of any micro-payment system is going to be the newspapers (that may or may not work for them, but they will try it), but how many old people are on facebook?

You mean the primary users of Facebook are the demographic buying content online through Xbox Live and phone app stores?

You don't need to be "on Facebook" to use their hypothetical micropayment system. Non-members can be shown a simplified sign-up page, like they would see if another company became the de-facto micropayment processor.

Facebook has over 200 million users. It's more than just "twenty somethings".

I was friended recently by someone I met on a trip to China. He is pushing 75 years old. Definitely not just twenty-somethings.

Their fastest growing demographic is women in the mid 30s, last I heard.

If they have some kind of payment system in the works - they definitely do, they were talking to platform developers about it a year ago (requests for feedback, NDAs, etc.)

I'm surprised they haven't moved faster with it. Sure, it could be vaporware, but given that it's a pretty obvious direction to go in, I really doubt it.