ie8 in beta
Web slices (think context sensitive right click-able options) and web activities (fixed web pages docked with event notification)
https://www.microsoft.com/windows/products/winfamily/ie/ie8/readiness/NewFeatures.htm
Definitely worth watching the videos and if you are web dev then downloading and prep'ing.
Nice feature I liked was the AJAX aware back button (goes back to the last navigation within a page)