This week players of Facebook games found themselves unexpectedly rewarded for their playtime. The frequent messages that Facebook has awarded the gamer with credits signals Facebook's push to implement Facebook Credits , a virtual currency intended to standardize payments across the multitude of Facebook applications. The push of the credits program has also signaled a rise in the number of scams centered around it.

The credits can be used for virtual items, gifts, and power-ups in games such as Bejeweled Blitz, Farmville, Mafia Wars and Treasure Madness. Facebook is using a "first taste is free" approach to hook users on credits. Users are seeing popups appear to inform them that they've won Facebook credits. (Users should be careful when claiming their prizes.)

The company's prepared for the push. It's made it as easy as possible for users can buy Facebook credits for 10 cents each --pay with credit card, Paypal or mobile phone. They can also earn credits by filling out surveys or through winning them in promotions .

Facebook's pushing credits through the MyTown application as well as others. Plans to sell Facebook credits in cyber-cafes and 7-11 stores are in the works. Leading game development company Playdom has signed a five year contract with Facebook to exclusively use its credits in its games. Playdom is the largest game producer on MySpace and the third largest on the Facebook platform.

This marks Facebook finally moving to an effective financial model, with an estimated $1 billion in revenue this year, leading blogger Chris Birk to speculate Facebook credits might become the first global currency . This makes the recent closing down of its lucrative gift shop program , which puzzled analysts, more understandable.

Benefits to developers for using the standardized system include increasing the market and making it easier for consumers to buy items. But Facebook Credits aren't free to use. Facebook charges a fee of 30 percent per transaction and moreover, spells out other restrictions on developers, such as restrictions on selling credits or accepting credits for tangible goods.Shawn Foust on VentureBeat offers a list of strategies for developers who want the advantages that Facebook credits provide , while minimizing their cost.