Taking my recent post:
as an example, it can be seen that there is a problem with the heading structure; an H1 for the post's title is followed H3s for comments ("One Response to Making a Difference to My Career", "Leave a reply") and then by H3s ("Recent posts", "Blogroll", etc.) for the right-hand column's sections, with no intervening H2.
Sequentially-nested headings, with no such gaps, are important for accessibility; see http://www.youtube.com/watch?v=AmUPhEVWu_E for a demonstration
A simple fix - and indeed a semantically helpful one, clustering like sections together - for this would be to create H2 headings at the top of the comments, and the right-hand that column (called, say, "Comments" and "Additional resources" respectively), and then to use CSS to float them -3000 pixels off the left hand edge of the screen.
Alternatively the exiting H3s should be marked up as H2s, but styled to maintain their current visual appearance.