Mobile data entry application (offline & online)

Looking for a HTML5, or equally capable native app for both iPhone & Android, front-end that interfaces with existing APIs. The application will consist of simple forms for data entry with the option to take the app offline in areas where there is no network connectivity. Data should be stored locally on the device when offline. Once the mobile device is back online the stored data will (automatically or manually) synchronize via the APIs. Login/logout functionality is also required and login state/credentials should persist when offline. There is a prototype application that was already started, developed in ExtJS 4.0 and utilizing HTML5 WebStorage for offline functionality. This will be provided to the developer for further illustration. Preference is given to the jQuery or ExtJS framework, however, actual technologies used will be left up to the developer if a demonstration is provided to prove similar capability. A bonus will be paid if the app is compatible with Windows Phone 7 and BlackBerry. If the project is developed and delivered on time and to full specifications there will be additional opportunities presented. Thank you.