Column groups allow authors to create structural divisions within a table. Authors may *highlight this structure through style sheets* or HTML attributes (e.g., the rules attribute for the TABLE element)[emphasis added].
Yeah. And the stylesheet spec says <http://www.w3.org/TR/CSS21/tables.html#q4>:
The following properties apply to column and column-group elements: 'border', 'background', 'width', 'visibility'
So you can't align via columns anyway, in CSS.
That said, we don't even support those four yet because it's the _one_ of the very few places in CSS where style applied to a node needs to be applied to random nodes that are not its children (the only other case I can think of the the body background mess, and that's hard enough to do in itself; the table stuff would be much more difficult).
