Hi Mike,
I'm currently using the new Admod. which is part of Google Play Services. I'm using Google Games, Plus, & Ads APIs, below is a link to another post I did on Google Play Services integration.
My Android class didn't change much from 6.4 except for the imports.
import com.google.android.gms.ads.AdListener;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdSize;
import com.google.android.gms.ads.AdView;
While Ads are included in Google Play Services library, Google Play Services is not require to be on the device to use Ads. Other APIs such as Games requires the service to be installed so you should check to see if its installed before using those APIs. This way you can have one APK that shows ads on all devices and will take advantage of Google Play Games if installed. Below is code related to use Play Games API and is not required for Ads, just in case you were interested.
//Setup Google Play Services for use in PlayN if installed
googlePlayStatus = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
if (googlePlayStatus != ConnectionResult.SUCCESS) return;
//Create Google Helper taken from Google sample code
if (mGoogle==null) mGoogle = new GameHelper(this, mRequestedClients); //Request APIs like Games, Plus. Ads don't be requested.
//Social Service is your class that implements an interface you define in your core project to allow game to access
SocialService s = new SocialService(mGoogle); //Create you class with the Google Game Helper class
mGoogle.setup((GameHelperListener)s); //Your Social Service will also implement the Game Helper interface
game.setSocial(social); //If your game your interface to your social class
Tim