I'm guessing most of the remaining IE6 installs are inside corporations and government departments and are necessary to run legacy internal web applications.
Again, same reply:
"That's not an excuse. IE 8 comes with a "compatibility mode" feature where any site can choose to use the IE 6 rendering engine by setting headers or meta tags appropriately."
Great! Explain that to IT. :)
True... but not by choice since some government agencies are still using Windows 2000 (which doesn't support IE7+). Some might say a move to FF would be beneficial, but the overhead of having to manage and secure FF is far greater when they can just stay on IE6.