Edit in JSFiddle

<h3>Products</h3>

<ul data-bind="foreach: products">
    <li>
        <strong data-bind="text: name"></strong>
        <em data-bind="if: manufacturer">
            &mdash; made by <span data-bind="text: manufacturer.company"></span>
        </em>
    </li>
</ul>
function appViewModel() {
    this.products = ko.observableArray([
        { name: "XBox", manufacturer: { company: "Microsoft" } },
        { name: "PlayStation", manufacturer: { company: "Sony" }  },
        { name: "Banana", manufacturer: null },
        { name: "Wii", manufacturer: { company: "Nintendo" }  }
    ]);
};

ko.applyBindings(new appViewModel());