DataGrid, grouping data by item property?


Anyone know if there is a way to group items in a DataGrid by an item property, fer example:

Say you have a list of products, and the products belong to categories, like, Summer products, Winter products…is there anyway to group products in a DataGrid under separate headers? IE: Winter (all winter products follow) Summer (all summer products follow). I can already order by category, but instead I want to do this:

Winter Category

  1. Winter Product 1
  2. Winter Product 2
  3. Winter Product 3

Summer Category

  1. Summer Product 1
  2. Summer Product 2
  3. Summer Product 3
  4. Summer Product 4

Do it need to create a DataGrid for categories and nested DataGrids for products per Category? Or is there some built-in way of grouping within a DataGrid?