Yeah, he’s right. I’m currently averaging about 150,000 impressions per day for all my apps combined. Revenue depends on a lot of factors, such as exactly how you are serving the ad, the keywords you’re using (if the service you’re using has keywords), and of course the arcane way in which advertisers actually bid for ad space.
I would also be curious to know if Kingaschi was actually accepted to the AdSense beta, and if so, how. The requirements are that you need to be able to serve up in the range of 100,000 impressions per day minimum.
If what you’re actually doing is using AdSense for mobile websites in your app (e.g. by serving them up in a webview), this is a big no-no and may result in you getting your AdSense account suspended. There was a case last year where this happened to another dev.
Those looking into serving ads in their apps may want to check out MobClix. I’m been experimenting with them in a couple of my less popular apps. Integration was fairly easy, and serving your own house ads was also very easy. However, as far as I can tell, you have far less control over targeting (e.g. you don’t set keywords as in AdSense).
I also saw a while back that GreyStripe had opened up a beta for Android, though I have no experience with them.