I may have changed my region to US to get Cortana, but this may be the second most useful feature after the Action Center in the update (at least until Cortana is out of Beta).
Weird, I have a new Surface Pro (that I picked up recently when it was on final clearance sale) and I believe the button is actually on it.
I updated my own Koodo Lumia 520 and from my experience I bet the update is just pushing out the very latest version of the OS to your handset as opposed to the version that Verizon and HTC...
Yeah, this should have been on the radar at least 10 years ago (and I among many was talking about it). Still, it's something Apple will have a very hard time competing with.
What I really need from Modern Skype is the ability to ring the call at the same time as I get the call on Desktop Skype and WP Skype, not half a minute after.