Using Mezzoblue is a bit of a tricky example. Dave Shea is a big Web Standards advocte, member of the Web Standards Project and that his personal page.
Its a blog type site with various bit of information he like to comment on. I get the issue with the nav links at the top right with Opera too.
If it were a commercial site, I imagine he'd be a bit more sure about it working across the platforms a bit more.
CSS is deffinately the way to go, Dave's other site
is an amazing example of what can be done with the same HTML, just different style sheets and images.
Having said that, in many commerical cases, it makes sense to use some tables too, to try and keep hold of as many customers as practically possible. Becoming more common is a kind of hybrid page. There may be one or 2 fairly simple tables for the overall page structure, while the rest is all done with CSS, including some other, smaller bits of positioning.
It doesn't have to be an all or nothing situation.