I’m also interested in solving this. We have abandoned NativeActivity 2 years ago because we couldn’t implement Admob over NativeActivity’s view.
Maybe something like this could work: http://www.dynadream.com/ddweb/index.php/Special_Blog?id=20
But needs testing(and maybe more work). As far as i can remember it didn’t work on my galaxy player with android 2.3.5. (checked some months ago)