Is this a sick joke? Besides the fact that the browser can trivially redirect to the exact app in the app store, I'm already annoyed that ABC wants me to download their god damn app everytime I accidentally click on one of their articles on Google News.
Not only that, but if the user has the app installed they're already prompted to open the same content with the app instead of the browser if they want.
This problem is already solved. This is very, very common in Android apps and I understand it is a new feature in iOS6 as well.
I guess if this is absolutely necessary, the browser could output a new header for domains that are declared in the .ipa/.apk that would notify the server that they have the app installed... and then they could force the app to open with a regular redirect. But that still majorly SUCKS to users who already have that choice anyway. If anything this gives the publisher more control of forcing me to use their app which I absolutely do not want.