The blog post mentions that the notifications API is for use by extensions and Chrome-based desktop apps. That means it's roughly equivalent to Firefox's XUL APIs, which are definitely not standardized.
Try going to http://www.hevanet.com/acorbin/xul/top.xul in Firefox: "This page uses an unsupported technology that is no longer available by default in Firefox"
Chrome apps are like Firefox addons, they have their own non-standard APIs. So complaining that Chrome Apps have their own non-standard APIs is not a valid argument when compared to Firefox.