Social game developer Playdom is the latest studio to sign a five-year contract with Facebook to exclusively use the social network's universal virtual currency Credits across all its titles.

The news follows just a few days after Disney announced its agreement to acquire Playdom for up to $763 million, a purchase that puts Facebook in the position to claim that Credits, which is currently in beta, has the support of a major media conglomerate, possibly compelling other companies to follow suit.

Inside Social Games, which reported the new contract, notes that developers such as Wooga (Monster World), LOLapps (Band of Heroes), RockYou (Zoo World), and CrowdStar (Happy Aquarium) have also announced agreements to exclusively use Credits, with the latter two signing similar five-year deals with Facebook.

With Credits, players can purchase digital goods in any social games that support Facebook's in-house virtual currency. The benefit of this system to users is that it's designed to be more portable than virtual currencies that they can only spend in a specific game or a catalog of titles from a single publisher.

Playdom, which will soon join the Disney Interactive Media Group if the acquisition is completed, offers dozens of titles on Facebook and MySpace. On Facebook alone, its games (e.g. Social City, Tiki Resort) bring in a total of more than 38 million monthly active users, according to figures from AppData.