I am also using CSS for layout, tables are for tabular data not layout and CSS should be used.
Check http://salsablanca.com it is a 3 column css only layout. To be honest it is a commercial site and I am not that worried that every browser works, but it should degrade successfully.
Also, I have css versions of ad_form etc at http://jongriffin.com/static/openacs/css-only/
