Microsoft surprised me that they didn't block out other browsers. Google didn't surprise me at all and the game is blocked in Opera. It works when user-agent is changed.
It's sad when company acting as someone for open and standard web is doing this. And Google is doing this user-agent sniffing across all their products.
That's probably it for some features but it still sounds like "You have to use IE5 or higher to see this site" to me.
Also, some features have been blocked for a long time for no apparent reason, for example background image on search. It worked from the day one (when you changed the user-agent), there is nothing scientific about it, yet it is still blocked years later.
It's sad when company acting as someone for open and standard web is doing this. And Google is doing this user-agent sniffing across all their products.