The site looks the same in Chrome, Firefox, IE9 and IE8 to me.
IE7 seems to have a gap. Perhaps it's caused by the empty clearing div between each entry. Try removing those and see if that stops the gap.
As an <aside>, it's strange that you've got your main content inside an <aside> element. How did this come about? I know HTML5 is confusing, but I didn't expect to see that.