Well the Google services are the "Core" services that you care about. Email, Browser, Google Now (all of the alert/notifications piece etc) Maps etc. So on an Android device once a month it seems like one of your major core apps is getting a meaningful overhaul. vs the Apple model where once a year or so you get a deluge of new goodies. And naturally other apps are always updating.

Then I guess there's been a big shift in Android's philosophy. Then Open Handset Alliance still says that "Android does not differentiate between the phone’s core applications and third-party applications." [1] But now it sounds like core applications get special treatment.

1: http://www.openhandsetalliance.com/android_overview.html

Android, the operating system, doesn't care at all if you replace the dialler, or the home screen app, or any other app.

What did happen about a year ago is google moved some of the communication framework stuff from android proper, and rolled it into 'google play services' so that it can be updated independently of the version of android on your phone.

As a result, apps like hangouts, plus, maps, the dialer and others which rely on those frameworks can be updated to use the newest version of the framework without worrying about the whether your population of phones have been updated to android x.y, any phone that has the play store installed and updated should be running a recent version of play services.

I believe what they mean is 3rd-party apps have the same access to the phone that our (Google's) apps do. The core apps aren't getting special treatment, Google is just deciding to update them more often than some of the 3rd-party apps out there.