Here is a tutorial on how to implement AdMob advertisements into Gideros exported Android project. Thanks to @Paolo Manna for provided examples.

First thing you need to know, that exported Android project is a single view appliation, meaning, right now there is now way (not that I know of) to control when, on which scene will advertisement appear. It means that advertisement will always be visible, you should design your app's layout accordingly.

So if you don't know how to export project and import it to Eclipse, here is an explanation on how to do it.

After your project is imported into Eclipse, go to AdMob website and download latest AdMob SDK (in this example I've used 4.3.1 version). Now you need to import SDK jar file into the project. To do that, right click on project and select properties, from there select "Java Build Path" and click on "Add External JARs..." and navigate to downloaded SDK to GoogleAdMobAdsSdk-4.3.1.jar file.

Edited: You need to check Admob plugin on Order and Export tab to export it to your app.

Next we need to modify AndroidManifest.xml by adding AdMob activity:

<activity 
	android:configchanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize"
	android:name="com.google.ads.AdActivity"></activity>

And user permissions:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

Resulting AndroidManifest as this example:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="com.yourdomain.yourapp"
 android:versionCode="1"
 android:versionName="1.0">
 <uses-sdk android:minSdkVersion="8" />
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
 <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"></uses-permission>
 <uses-permission android:name="android.permission.INTERNET"></uses-permission>
 <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>
 <uses-permission android:name="android.permission.VIBRATE"/>
 <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

 <application android:icon="@drawable/icon" android:label="@string/app_name" android:theme="@android:style/Theme.NoTitleBar.Fullscreen">
 <activity android:label="@string/app_name" android:name="com.giderosmobile.android.ElasticJointActivity" android:screenOrientation="portrait" android:configChanges="keyboard|keyboardHidden|orientation|screenSize">
 <intent-filter>
 <action android:name="android.intent.action.MAIN" />
 <category android:name="android.intent.category.LAUNCHER" />
 </intent-filter>
 </activity>
 <activity android:name="com.google.ads.AdActivity"
 android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize"/>
 </application>
 <supports-screens android:largeScreens="true"
 android:smallScreens="true"
 android:anyDensity="true"
 android:normalScreens="true"/>
</manifest>

By default there is only one view, where Gideros resides, but we need to create second view where to show advertisement, so we'll create one wrapper layout, in which we'll include Gideros view and Admob advertisement view. So we need to create an XML file with defined layout and save it inside "res/layout"  folder. Don't forget to refresh your pojects (Right click on project - Refresh or simply F5) after adding new files to it. Let's name this main layout as main.xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 android:gravity="bottom"
 android:id="@+id/layout_main" >
</FrameLayout>

Next in Eclipse in your project you need to open folder src -> com.giderosmobile.android -> YouAppName.java

First we need to import AdMob's com.google.ads library in the beggining of the file, where everything is imported:

import com.giderosmobile.android.player.*;

import com.google.ads.*;
import com.yourdomain.yourapp.R;

Next in the beggining of Activity we need to define an adView variable:

public class ElasticJointActivity extends Activity implements OnTouchListener
{
	private AdView adView;

	private GLSurfaceView mGLView;
	private AudioDevice audioDevice = new AudioDevice();

And inside onCreate method we need to comment out setting Gideros view and instead set our own layout we defined in main.xml file, add both adView and Gideros view to main layout and request an advertisement:

public void onCreate(Bundle savedInstanceState)
{
	super.onCreate(savedInstanceState);
		
        mGLView = new GiderosGLSurfaceView(this);
	//setContentView(mGLView);
        //set new main layout
      	setContentView(R.layout.main);
      	
	mGLView.setOnTouchListener(this);
                
        JavaNativeBridge.setActivity(this);
	JavaNativeBridge.onCreate();
		
	// Create the adView with your publisher ID
 	adView = new AdView(this, AdSize.BANNER, "a14f6250f698606");

	//get main layout
	FrameLayout layout = (FrameLayout)findViewById(R.id.layout_main);
	    
	//this can be used to change position of advertisement
	//change Gravity.TOP to Gravity.BOTTOM if you want ads to appear in the bottom
	    FrameLayout.LayoutParams adParams = new FrameLayout.LayoutParams(
	    			FrameLayout.LayoutParams.WRAP_CONTENT ,
	    			FrameLayout.LayoutParams.WRAP_CONTENT ,
	    			Gravity.TOP);

	// Add the Gideros view to main layout
	layout.addView(mGLView);
	// Add the adView to main layout
	layout.addView(adView, adParams);

	// Initiate a generic request to load it with an ad
	adView.loadAd(new AdRequest());
}

And last thing to do is to destroy advertisment in class's destructor:

public void onDestroy()
{
	//destroy add
	if (adView != null) {
		adView.destroy();
	}
	JavaNativeBridge.onDestroy();
	super.onDestroy();
}

And that's it. You can download example exported project with implemented AdMob advertisements and here is the result, how it would look like: