Facebook and game-creator Zynga yesterday announced they’ve entered a five-year strategic relationship that, in part, will expand the use of Facebook credits as a payment system. The deal has some implications for those in online media and Internet marketing.

Zynga is the behemoth company that has created prominent Facebook games such as Farmville, Mafia Wars, Cafe World and Treasure Isle. It’s good news if you love these type of social games. On the other hand, non-gaming Facebookers will have to continue enduring game updates from their FB friends. (There’s plenty of coverage of the deal, including this post on TechCrunch.)

For online-media and Internet-marketing types, the announcement reinforces what many have already figured out — online, social gaming will continue to grow. The key implication is that while people are playing their games, they’re NOT consuming other media. It might be time to add games to the list of internet marketing tools, which already includes SEO, SEM, e-mail, websites, web landing pages, display ads, etc.

I’ve not yet tried Farmville (I confess to experimenting a little with Warstorm, which is produced by Challenge Games, not Zynga), but is there a way to market products there? Can Agway have a store in Farmville? Can Domino’s Pizza supply “energy” in Mafia Wars?

Marketers should also consider whether they can build a game around their product. Here’s a marketing-game case study I first heard about two months ago at OMMA Global in San Francisco. Last year, Volkswagen marketed the 2010 version of its GTI by using a mobile game called Real Racing GTI. It didn’t buy any media — none, zip, zero, $0. The result: The game — available only from Apple’s iPhone App Store, became the number one download in 36 countries. Eight car sales were directly attributed to the game in the first week. So far, 175 sales have been attributed to the game. The cost per sale was reduced 97 percent. And 50 percent of the sales of GTIs were to folks who had never before owned a VW. The normal rate is 25 percent.

The second development to watch as a result of the Facebook-Zynga partnership will be the development of the Facebook credits payment system. It may well be the micro-payment model that folks in online media have been seeking. And for other businesses, it might open doors to sell “products” that are purely electronic.

Online media professionals and Internet marketers should be able to mine ideas and inspiration from new developments in social media like the Facebook-Zynga partnership.