Heres an article about the new release of IE8 RC1 and the improvements over the beta versions.

IE8 is a major shift by Microsoft to Standards Compliance using XHTML 1.0 Strict. Boonex claims it's DOCTYPE is XHTML Transitional but when you run any Boonex page through the Markup Validator at http://www.w3.org/
you find hundreds of code validation errors. Firefox 3 is already compatible with XHTML 1.0 Strict.

http://www.winsupersite.com/live/ie8_rc1.asp