How to modify the default Gruntfile generated by generator-backbone to support building assets into a Phonegap app nested inside the project.

Gruntfile.with-phonegap.js

// ...

module.exports = function (grunt) {
    // ... 

    // configurable paths
    var yeomanConfig = {
        app: 'app',
        dist: 'dist',
        phonegap: 'phonegap/www'
    };

    grunt.initConfig({
        
        // ...
        
        clean: {
            dist: ['.tmp', '<%= yeoman.dist %>/*'],
            phonegap: ['<%= yeoman.phonegap %>/*', '!<%= yeoman.phonegap %>/config.xml'],
            server: '.tmp'
        },
        
        copy: {
            dist: {
                // ...
            },
            phonegap: {
                files: [
                    {
                        expand: true, 
                        cwd: '<%= yeoman.dist %>',
                        src: ['**'], 
                        dest: '<%= yeoman.phonegap %>'
                    }
                ]
            }
        },
        
        // ...
        
    });

    // ...
    
    grunt.registerTask('build', [
        // ...
        // Change 'copy' -> 'copy:dist'
        'copy:dist',
        // ...
        // Update Phonegap www
        'clean:phonegap',
        'copy:phonegap'
    ]);
    
    // ...
};