Thanks for sending that. I haven't actually looked at validations lately.
The vast majority of the validation failures are custom attributes, which we rely upon heavily, but it looks like HTML5 now has a way to do that: http://www.javascriptkit.com/dhtmltutors/customattributes.shtml
We'll consider whether we should convert custom attributes to validation-friendly format
As of Wagn 1.12, default Wagn pages will be completely valid html. See http://validator.w3.org/check?uri=http%3A%2F%2Fen.dwagn.org%2F
(please report any exceptions!)