I could see several uses for an API that returns information about registered apps.
The most obvious use would be sites that rank or help users discover new apps, similar to AppShopper for iOS apps.
If the features are provided, reporting "rogue" apps could be done in a more structured fashion, just like reporting users for spam.
A client could also pop up a window with information about an app rather than just opening its webpage when the app name is clicked. This keeps the user in the app, which is always a good thing. Disrupted context is unnecessary and discourages users from clicking app links, and thus discovering other apps they may like.
(Of course, developers would have to be able to mark their internal apps as hidden…)
I could see several uses for an API that returns information about registered apps.
(Of course, developers would have to be able to mark their internal apps as hidden…)