Well, I found a solution, but I don’t know if it’s the proper way of doing things. I went ahead and placed the statement $full_title = '';
on line 23 of wp-e-commerce/widgets/category_widget.php. If anyone knows of a better way, I would appreciate any comments.
I had the same problem with the Tag Cloud widget. If you leave the Title field blank in the widget admin it will display a default title above the Tag Cloud. To get around this you can type a single space in the Title field and it will remove the default title.