I found a nice document at Microsoft Download showing all the new features in Internet Explorer 8  which is currently in beta:
Reach Beyond the Page. Internet Explorer 8 includes new features that help people more efficiently use the Web. Accelerators (one is shown on the next page) make it easier to take action on information on Web pages, and Web Slices enable them to instantly monitor changes on sites of interest. In addition, the Search Box in Internet Explorer 8 has been improved to allow search providers to deliver rich, visual search suggestions in real time, as users type a query.
Safety, Choice, and Control. Internet Explorer 8 delivers improved protection against security and privacy threats, including the ability to help identify malicious sites and block the download of malicious software. Privacy is enhanced through the ability to surf the Web without leaving a trail on a shared PC, and through increased choice and control over how Web sites can track user actions. Internet Explorer 8 also helps inspire confidence and trust through improved restrictions for ActiveX controls, enhanced add-on management, improved reliability (including automated crash recovery and tab restoration), and enhanced support for accessibility standards.
Download and read the complete Internet Explorer 8 evaluators' guide .
When you read the document you'll find a demo site  that will show all the new security, interoperability and advanced AJAX features in IE8 without having to search for sites or visit potentially dangerous sites.
The main topics there are:
The Web site referenced in this guide (www.ie8demos.com/tryit ) for experiencing some of the features of Internet Explorer 8 is password protected. The username is ie8demo and the password is ie8dem0 (the last character is a zero).