It's pretty clear by now that Facebook is banking a lot on its new App Center. It's going to further Facebook's goal of having a hand in every piece of Web traffic as it helps connect users to their favorite applications on the Web. What we don't know yet are specifics, but Facebook has been slowly trickling them out.
One of the more ambiguous bits was how App Center was going to handle mobile apps. After all, App Center is for both Web and mobile applications. Considering how much of an impact Facebook has had on mobile in the past year since Open Graph has launch, it's a no brainer that the company would put a big emphasis on mobile.
Before we get into anything else, Facebook wants to make it clear that mobile apps are not hosted on App Center. None of the apps that you're going to see on App Center will be hosted there as it's more of a portal to finding your favorite apps instead of being a repository.
From there, users can search for their favorite apps that use Facebook login via App Center. When they find an app they're looking for, hitting the install button will take them to that app's page on iTunes or Google Play for install.
Now here's where things get pretty cool. If the user in question already has the app installed on their phone, App Center will open that app for them and have them automatically logged in via Facebook. Sure, you can open an app from your phone's menu, but Facebook removes the tedium of having to login.
What if the person in question is browsing App Center on their computer? Your app's detail page will have an option at the top right that says, "Send to Mobile." From there, it will send the user a Facebook notification to their phone that prompts them to download the app from iTunes or Google Play.
If you're interested in getting your mobile app listed on App Center, the app must use Facebook Login. You don't have to exclusively use Facebook for the login process, but it must be an option. You'll also have to create an app detail page. While the deadline to be listed for the launch of App Center has already passed, you can still apply.