post.js.jsx

// ...

var PostHeader = React.createClass({
    render: function() {
        return (
            <div className="post-header">
                <h2>{this.props.post.title}</h2>
                <div className="post-meta">
                    By {this.props.post.author} – {this.props.post.created_at}
                </div>
            </div>
        );
    }
});