http://eddiekim.posterous.com/selling-shovels-to-android-gold-miners
Stealing apps is trivial. just do a google or twitter search for your application’s .apk file and it’ll be posted somewhere on the internet. A user need only to copy this .apk file to his/her phone to pirate it. I collected some data and found that Car Locator had an 80% piracy rate. That is, for every 1 person who bought the app, 4 people were pirating it. Google did release a licensing system, but as they posted on their blog, it has already been cracked.