One of the first things I noticed about Facebook's latest redesign was a new tab called "Credits Balance" that showed up in the "Accounts" section near the upper right-hand corner of the screen. Facebook Credits are the social network's branded currency; people can use the credits to give virtual gifts, including MP3s, as well as for payment in certain social games.

"So, the new FB design has a tab specifically for 'credits'," I tweeted. "They are serious about micro-payments and virtual goods, eh?"

And with today's announcement that Facebook is integrating PayPal as a payment platform, it's clear that I was right: Facebook is very serious about making virtual goods and micro-payments a sigificant source of revenue. The news also shows that the network wants to make it easier for advertisers overseas to spend money trying to entice its increasingly global audience. Here's why:

Pay me with PayPal

Previously, it was much harder to check your credits, as the tab was somewhere unintuitive. Now, people are reminded that they have a "Credits Balance" every time they want to edit their profiles and change privacy settings. Subtle and subliminal, perhaps, but it will definitely spark curiosity -- not to mention create familarity -- with the idea of paying for things on Facebook.

This follows a shift by Facebook to put up what's essentially a big banner ad on someone's profile on their birthday, asking friends that visit if they want to give a gift. The ad links to a payment page that asks for credit card info. Ultimately, the PayPal integration means that people won't have to enter credit card info; they'll be able to login via PayPal and spend $2 here, $5 there for profile badges, MP3s, and of course, weapons for Mafia Wars.

Facebook has been testing its payments platform since last May, though mostly in stealth mode (per VentureBeat). It added the MP3s through a partnership with LaLa last October (via paidContent), and the addition of PayPal means it will be able to take payments from users without credit cards and in various countries.

"App developers like Zynga have been using PayPal for their Facebook games since Facebook first opened up is platform to e-commerce," said PayPal spokesperson Anuj Nayal. "But now, we're integrated directly into Facebook's Credits system, meaning that payments don't have to just be for specific games."

Nayal wouldn't disclose whether Facebook would pay out a per-transaction fee or a percentage of the gross amount spent over a given amount of time, but he made it clear that Facebook users wouldn't bear any of the costs. "It works like any other merchant service agreement; we take a percentage from the merchant -- not the customer."

International ad revenue

Meanwhile, the addition of PayPal as a payment system for ads means that it's easier for smaller companies (both here and abroad) to spend money on Facebook ads. "Something like 70 percent of Facebook's hundreds of millions of users don't live in the U.S.," Nayal said. "Advertisers in those countries might have wanted to reach them, but they had no easy way of paying for it."

Once fully rolled-out, the PayPal-Facebook integration will support 24 currencies and businesses in 190 countries. Guess Facebook's COO Sheryl Sandberg was serious when she told Bloomberg that the company needed to prove to investors that it could really make money this year.