Two requirements need to be met before browser based technologies are capable being a general replacement for applications:
1. They need to be functional offline. The ability to edit a document can’t depend on the availability of a network signal.
2. There needs to be access to core phone features like the phone book, calendar, camera and location.

Those requirements are also valid when you are considering developing a mobile application and you are hesitating between developing a mobile web application or a native application. To which I would add two other points…
3. Needs of updating the application. Mobile web app are much more easily updatable. It takes much more time on a native application.
4. Portability on any device. When well done, a mobile web application can be accessible from the begining to almost any mobile device. Ain’t true for native app obviously.

To sum up… things to think about when developping a mobile web app. vs. a native app:

1. Offline feature.
2. Accessing core feature of the phone.
3. Ease of update.
4. Portability on any device

I’ll end with a quote from Cameron Moll on Twitter:

…and the more I’m convinced well-done mobile web apps pretty much negate the need for iPhone installed apps that do the same.