Yes? Other people had already mentioned some in this thread.
Generally: Any circumstance where you might want the icon to change per section/page/app rather than per (sub)domain. Do you want me to enumerate all possible combinations of web server configuration and tick the ones that applies to?!
For one: perhaps you host several tools off the same domain name, either literally on the same web server or via a proxy arrangement. As I said, these circumstances aren't all that common, and when they turn up I doubt the right favicon being use is going to be something you'd care about overly, but I wouldn't be surprised to find there are circumstances where it is important enough to someone.
Generally: Any circumstance where you might want the icon to change per section/page/app rather than per (sub)domain. Do you want me to enumerate all possible combinations of web server configuration and tick the ones that applies to?!
For one: perhaps you host several tools off the same domain name, either literally on the same web server or via a proxy arrangement. As I said, these circumstances aren't all that common, and when they turn up I doubt the right favicon being use is going to be something you'd care about overly, but I wouldn't be surprised to find there are circumstances where it is important enough to someone.