[stevewodil]

Oftentimes it has to do with the native APIs that are available.

I'm building an app, and being able to deliver a better experience when selecting an image/video to upload was a consideration and one reason why I didn't use a mobile site and instead went with an app.

Push notifications are another big appeal of apps vs. a website, although I know that has changed somewhat recently it probably won't cause any massive shift in mobile site development.

Oh, and tracking :)