At the moment the way to add categories for List Items is if you declare a custom taxonomy field for your list items. The design for the Lists module is to use the parent list for grouping and not other fields. So essentially if you want to group items by criteria you should create different lists.
The RadListView control supports grouping, however since the taxonomies field is an artificial field which allows you to map to more than one category at a time you will not be able to do this with the built in widget. The approach here would be to create a custom control for displaying list items and to get filter items by category and then bind them
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