There has been a lot of talk on HTML5 and how it is just as good as native phone apps. The biggest factor that has been holding it back is getting your HTML5 app found. The web being the wonderful place it is has provided ways to get around that with app stores like openappmkt. On a phone, the default market or store will be the native store of the device. Other App stores won't be found by the majority of users.
The benefits of using HTML5 Apps should be obvious, smaller development cost and greater device reach. It would be nice if the mobile app stores supported HTML5 without the need for a third party tool to prepackage your app. Hopefully that day will come.