Yahoo! has not introduced anything new they have just customized IE 7 beta 2 to meet their needs. Yahoo! has used the beta version of the Internet Explorer Administration Kit (IEAK) to customize IE7 beta 2. It is available to all developers and partners who want to create their own customized versions of IE7, as well as IT pros who want to use it to ease enterprise deployment.
Download Yahoo! optimized IE7 beta 2