Here is my latest CSS based site - http://www.damnwitty.com - no tables in the skin, valid XHMTL transitional and CSS. It also passes automated 508 validation. I haven't removed all the tables from the core modules, eg the links module.

It wasn't that difficult to get DNN to produce code that validates.

A few changes to the default.aspx. Amend a few features in the dotnetnuke.dll where uppercase are tags are hardcoded and the id's are generated with a leading underscore.

In the skin I use Tim Roland's HouseMenu (free from http://houseofnuke.com/ ) and Scott McCullloch's Top Menu (by subscription from http://www.ventrian.com - well worth it!)  for the menus - as Solpart is a problem in Firefox as well as not validating. A couple of tweaks to the modules, eg the HTML module writes everything inside a span when it needs to be a div to validate.

Finally a few tweaks to the CSS to remove dimgray and a couple of other oddities.

it's being worked on, I blogged an approximate roadmap @ http://www.dotnetnuke.com/Community/BlogsDotNetNuke/tabid/825/EntryID/474/Default.aspx . One of the key areas was the addition of skin level doctypes http://www.dotnetnuke.com/Community/BlogsDotNetNuke/tabid/825/EntryID/1231/Default.aspx and http://www.dotnetnuke.com/Community/BlogsDotNetNuke/tabid/825/EntryID/1226/Default.aspx.

 In the past few versions we've made a number of fixes and enhancements (including removing the xhtml legacy compliance setting in 4.5), and will continue to do this for the next few versions (we're still discussing how best to integrate the new changes, but look out for some new skin objects and sample css-based tableless skins).

Cathal