As many web developers know, getting web sites working with Microsoft's Internet Explorer (especially IE6) can be frustrating at best. Unfortunately, IE is the most popular browser, so not supporting it is simply not an option.
As the newer standards based HTML 5 web technologies become available on browsers such as Firefox, Safari, and Opera, supporting IE will become an even a larger burden for developers. And in many cases, it is not in the best interest for some large players (Microsoft and Adobe included) to quickly rush adoption of these new standards. The recent InfoWorld article regarding HTML 5 explains aspects of this in detail.
This whole thing got me wondering if a plug-in approach could be used for adding alternative rendering engines into IE itself. All it would take is for someone to create an IE plugin (i.e. BHO or Content Extension) with the open source WebKit rendering engine at it's core. A little bit of redirection magic when IE is detected, sends the user to a page to install and launch the IE WebKit add-on, and we're done. This same approach works for Adobe Flash and Microsoft Silverlight. Why not for viewing HTML 5 documents?