phonegap(now Apache cordova) makes available the ios/android native features like camera,device file management,contacts,geolocation etc to our app.
GWT and mgwt :::
Using mgwt,gwt( both are opensource) and GwtPhonegap we can develop cross platform mobile applications which can behave exactly like native apps. in performance perspective these apps are bit slow when compared with native apps but the convenience is that the app can be installed in multiple platforms.
GwtPhonegap acts like a bridge(provides abstraction) between device native functionalities and to our app. We can get good look and feel using css.
We have support for gwt-html5-database for which to perform cache storage.gwt-html5