After threats and rumours of break up, Facebook and Zynga have announced that they have struck a long-term, five year deal to keep games like FarmVille on Facebook.

Zynga, who had previously threatened to set-up its games on external websites, will use Facebook’s currency system, Facebook Credits, in its games. Facebook receives 30% of transactions using the Credits, which was seen as an issue Zynga and the social network had previously fought over. The exact terms of the deal were not released, however.

While Facebook would receive this sizeable chuck of Zynga’s income, in return the social gaming developer would still be able to access Facebook’s huge amount of users. If the company had broken away it would be questionable if their players would follow them, as Facebook’s social features were a large attraction.

What this highlights mostly is the obvious co-dependent relationship Facebook and Zynga have with each other. Without Facebook’s users, Zynga is just another games company and as Venture Beat points out, the social games mean users keep coming back to Facebook to water their precious carrots. It looks like Facebook’s latest controversy is over, but I’m sure the company will soon do something even more abhorrent to piss everyone off. Something to do with privacy, perhaps?