Inflating Action bar item

Here is some example code that worked for me.

1: Create a layout for your badge menu item.

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="48dp"
    android:layout_height="fill_parent"
    android:layout_gravity="right" >

    <!-- Menu Item Image -->
    <ImageView
        android:layout_width="48dp"
        android:layout_height="fill_parent"
        android:clickable="true"
        android:src="@drawable/bkg_actionbar_notify_off" />

    <!-- Badge Count -->    
    <TextView
        android:id="@+id/actionbar_notifcation_textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:padding="@dimen/padding_small"
        android:text="99"
        android:textColor="@color/holo_orange_dark" />

</RelativeLayout>

2: Create a menu item in res/menu and set the actionLayout to your layout

<menu xmlns:android="http://schemas.android.com/apk/res/android" >
    <item
        android:id="@+id/badge"
        android:actionLayout="@layout/actionbar_badge_layout"
        android:icon="@drawable/icn_menu_posts"
        android:showAsAction="always">
    </item>
</menu>

3: Then in onCreateOptionsMenu of your activity or fragment you can do something like this...

public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    inflater.inflate(R.menu.badge, menu);

    RelativeLayout badgeLayout = (RelativeLayout) menu.findItem(R.id.badge).getActionView();
    TextView tv = (TextView) badgeLayout.findViewById(R.id.actionbar_notifcation_textview);
    tv.setText("12");
}

Note: If you wanted to change the badge count later on, you could store a reference to the Menu object passed to onCreateOptionsMenu and use the same code to get the required view and set a value.