I've just finished my new site and was testing it in different browsers only to discover that it wasn't displaying correctly in IE.
After lots of playing around disabling different plugins I discover that it was W3 Total Cache that was causing the problem. I've now disabled the minify element and the site is displaying correctly now.
If I re-enable it the problem recurs, I've tried it on both the auto and manual setting and it's the same for both. My site displays correctly with minify enabled in Chrome and Firefox 3.6, so it would seem the problem is isolated to IE.
The problem primarily effects the cufon fonts - some don't display properly; the right sidebar widget - this displays the widgets below each other rather than being able to switch between them using the 'more' button; and center text display on sub-pages and the blog - the height is reduced to about the same height as the sidebar widgets, rather than being the full screen height.
It's currently disabled so the site works correctly, but I can temporarily re-enable it if you need to to do so to be able to investigate.