Facebook has launched its new Universal app. The absence of a Facebook app in the App Store had paved the way for third-party developers to build Facebook apps using only developer API’s. To be clear, there’s nothing illicit or shady about these apps. Apple or Facebook would have shut them down if they were; Facebook was probably happy that their users’ needs were being served by iPad owners who weren’t satisfied with using the iPhone app from their iPad. It’s simply an opportunity that a number of smart developers took advantage of.

The real question is: Could these apps maintain their traction in the presence of an official app? In other words, was this a fleeting opportunity, or is there still a market for unofficial Facebook iPad apps (a scenario that the world of Twitter developers is all too familiar with)?

We followed up on the ranking of those unofficial iPad apps for Facebook (see the graphs below, courtesy of App Annie). There is a clear trend: Friendly for Facebook, Plus for Facebook, and MyPad’s rankings are gradually dropping everyday since the launch of the Facebook iPad app on October 11th.

Official Facebook apps cover most of the needs of their users. It is going to be interesting to observe how those apps pivot to keep and retain their user base.

[UPDATE] : Techcrunch wrote a post about MyPad and says “despite the launch of the official Facebook app earlier this month, MyPad usage is still at an all-time high, and growing.”. Their active user base may still be active but will certainly loose momentum growth as can be observed on ranking growth.