OK probly well known by now. But if you’re site is ‘broken’ in IE8, you could try the following which tells IE8 to work liek IE7.
<meta http-equiv=”X-UA-Compatible” content=”IE=7″ />
It belongs in the document’s HEAD. More importantly it needs to be preferably at the top of the HEAD section before any css, linked files etc.
The rule of thumb is, that the IE 8 meta tag needs to be placed above any linked files.