Edit in JSFiddle

var FooView = Backbone.View.extend({
    bindings: {
        '#firstName': 'firstName',
        '#lastName': 'lastName',
        '#fullName': {
            observe: ['firstName', 'lastName'],
            onGet: function (values) {
                return values[0] + ' ' + values[1];
            }
        }
    },
    initialize: function () {
    },
    render: function () {
        this.stickit();
        return this;
    }
});

var fooModel = new Backbone.Model();
fooModel.set({
    firstName: 'Taro',
    lastName: 'Yamada'
});

var fooView = new FooView({
    model: fooModel,
    el: $('#foo')
});
fooView.render();

<div id="foo">
    <p>First name:<input id="firstName"/></p>
    <p>Last name:<input id="lastName"/></p>
     <h2>Hello, <span id="fullName"></span>!</h2>
</div>