It's becoming more and more apparent that Microsoft isn't pleased with how well alternative browsers are doing, primarily Mozilla's FireFox. It was still a shock, however, to learn that Microsoft may simply deny services on their site to FireFox users. If you happen to have both FireFox and Internet Explorer on your machine, you can try it for yourself. Visiting Microsoft's preview page for their redesigned site in IE presents you with their new tools and the new site. Visit it with FireFox, Opera or a number of other browsers and you get “page cannot be found”.
Interestingly enough, even telling Opera to identify itself as IE 6.0 still results in the page not loading. Cracking open IE, however, has it working just fine. While Microsoft is fully within their own rights to design their web pages how they wish, it does have a hint of them trying to lock in a userbase. No word from Microsoft yet.