Gee - Microsoft reinvents IMAP

Terry Gray points out that Microsoft has announced that Exchange will be able to "push" email to mobile devices. While I'm sure they've invented some clever and entirely proprietary way of accomplishing this, Terry sez:

I sure must be missing something... all this hubbub about "push" mail, which sure sounds like what we've been calling "online" access mode in the IMAP context for over a dozen years.

Why use a real standard when you can invent one of your own?