woothemes/woocommerce — pull request #581 by pixeltrix (2012-02-06 12:46:11+00:00)
Title: Make product category URLs heirarchical

Heirarchical URLs for custom taxonomies is an opt-in feature added
in WordPress 3.1. This commit enables that support by adding the
appropriate flag to the rewrite setting for the product_cat taxonomy.

It may be preferred to make this a setting for backwards compatibility,
if so just say where you want it added.