We already knew about No Execute protection and some of the enhanced Internet Connection Firewall material, but up until now MS hadn't indicated exactly what was intended for Internet Explorer.
On Friday, I was going to make a post comparing Internet Explorer to a running sore on Microsoft's general reputation, but I think that's now redundant; they clearly are doing something about it. I only hope that IE 6.05 (as the alpha version in Longhorn build 4051 is called) is released for all MS desktop operating systems at the same time (or even earlier if it's completed first).
There's a lot of expansion in other areas, but there's still a lot more to come. Unfortunately there's no subscription link that I can see. This article was posted without fanfare on TechNet.