There's nothing built-in to do this. Just make an ImageView
in one of your view layouts and point it at the icon resource. Style and adjust to your tastes.
<ImageView android:src="@drawable/icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
If you want your image to be part of the grey title bar that appears by default in activities, I don't think you can do that - but you can easily turn off this title bar and just make your own. To turn off the title bar, just set the theme for the activity in the AndroidManifest.xml
file.
android:theme="@android:style/Theme.NoTitleBar"