Unfortunately, IE chokes on application/json. So its actually safer to use application/javascript, or even text/html instead.
This was still present in IE7, but they may have fixed it in IE8.
This was still present in IE7, but they may have fixed it in IE8.
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.