Index pages for custom post types (WP 3.1-RC1)

I had created a custom post type (twec_product) with rewritten slug “product” before upgrading to 3.1 RC. I then upgraded to 3.1 RC1 in order to test the new “index pages for custom post types” feature.

The following is a URL for one of my custom products:
https://thewebalyst.com/products/wordpress-website-set-up-launch-package/

From ticket 13818 I assumed the following URL should automatically provide an index of my products: https://thewebalyst.com/products/

As does every obvious URL variant I could think of.

Have I misunderstood what functionality is supposed to be here?

If not, how can I have a custom post type, with ‘slug’ rewritten as “products” and this not work?

Here is the code in the plugin I used to enable this post type (set up in WP 3.0.2, now upgraded to WP 3.1 RC1):

function create_post_type() {
  register_post_type( 'twec_product',
    array(
      'labels' => array(
        'name' => __( 'Products' ),
        'singular_name' => __( 'Product' )
      ),
      'public' => true,
      'rewrite' => array('slug' => 'products')
    )
  );
}

add_action( 'init', 'create_post_type' );