As Dean announced, a beta version of Internet Explorer 8 will be released in the first half of 2008.
The HTTP headers of every web request contain a simple string called the "User-Agent" that allows servers to identify the type and version of the visitor’s browser. For a deeper understanding of the User-Agent string, please see Understanding User-Agent Strings.
When released, the IE8 beta will introduce an updated User-Agent string. For IE8, we’ve simply replaced "MSIE 7.0" with "MSIE 8.0". For example, on Windows Vista, IE8 sends: