There's all kinds of client side uses for APIs. Facebook Connect logins for instance, which can't be initiated server side. Sending application/json to older v

There's all kinds of client side uses for APIs. Facebook Connect logins for instance, which can't be initiated server side. Sending application/json to older versions of IE can cause it to pop up Save As dialogs, even in AJAX requests. They did the same thing with application/xml+xhtml.