Internet Explorer 8 Beta 1

Security, ease of use, and improvements in in RSS, CSS, and Ajax support are Microsoft’s priorities for IE8. IE8 will run on both Windows Vista and Windows XP.

To soften compatibility issues with web pages designed around the bugs and quirks of Internet Explorer 7, Internet Explorer 8 will enable web designers to turn off all breaking changes in IE8. When a special meta element or its corresponding HTTP header is included in a web page, IE8 will render that page exactly like IE7 would.

Official Website

http://www.microsoft.com/windows/products/winfamily/ie/ie8/

Source