Here’s a story which, while it gets some details wrong, gets the point right.
IE 8 is the first browser from Microsoft that runs in “standards mode”. This means that it doesn’t accept HTML with quirks and non-standard extensions. Ironically, most of those quirks and non-standard extensions were created by Microsoft in older IE browsers. Most non-Microsoft browsers tend to come at this from a different angle. They adhere to standards but allow non-standard code when it doesn’t conflict with the standards. IE 8 appears to be taking a stricter view.
The story talks about a list of sites maintained by IE 8 that automatically switch it from standards mode to quirks mode. The headline is that microsoft.com is on the list. But that’s smoke and mirrors. The point is that the browser is very strict about what it accepts.
This is an issue that we will have to face as corporations deploy Windows 7/IE 8 internally. Sites we build or maintain for them will start to break with IE 8 if they’re not built with standards in mind. My assumption is that corporations can add their own internal sites to the exemption list but this will have to be deployed out to corporate desktops. For cross-browser support and simplicity in deployment, it’ll be better just to build standards-compliant sites.