Products Sub Category Widget for Market Press

Marketpress uses wordpress taxonomies to implement product categories, so have the ability to have hierarchical product categories (sub-categories)

Marketpress come shipped with a sidebar widget for product categories, but in conjunction with the standard wordpress categories widget, it does not traverse down subcategories.

Before I put pencil to coding pad, has anyone solved this, created similar or have a recommended sub-category widget that I can adopt?

(or maybe I missed this and there is a sub-category hidden somewhere in marketpress)