Here are some features highlighted by the product team as favorites:
Accelerators - Highlight an address, click the blue button and hover over “Map” or try Right Clicking a Page and Choosing Translate with Windows Live. Check out the new IE Gallery that has cool accelerators and slices from Digg to FaceBook to Ebay
Web Slices - Visit Live Search, search for “Seattle Weather” (or major city relevant to your region), hover over the rich search result and click the green button. Click it to add a Weather Web Slice to your Favorites Bar
Search Suggestions - Go to your Instant Search Box (top right) and type a search to see search suggestions in action.
Navigation - Use the new Smart Address Bar to quickly find sites you’ve visited before. The Smart Address Bar searches your history, favorites AND feeds for pages that match what you’re typing
Security: IE8 has the best security features in the market today from its updated Smartscreen phishing and malware filter to domain highlighting to the industry leading cross-site scripting filter so I feel my machines, my identity and my family will be safer on the Internet