This CellRenderer should do the trick:

public class ComponentRenderer implements TableCellRenderer {
       public Component getTableCellRendererComponent(JTable table, Object value,
                       boolean isSelected, boolean hasFocus, int row, int column) {
               if( value instanceof Component )
                       return (Component)value;
               return new JLabel(value.toString());
       }
}

Register it at your table-containing table with
       setDefaultCellRenderer(Object.class, new ComponentRenderer())
and you're clean.