There's a cart rendered for grouped products in Mage_Checkout_Block_Cart_Item_Renderer_Grouped, but it doesn't appear to ever be used. Am I wrong on this one? Anyone got the back story here?
Edit: @oleksii.svarychevskyi pointed out that the block appears in the layout XML files. Still, I have the question - since grouped products are added to cart as their individual simple components, and not presented as members of a grouped product, is this block ever used?