1. Android.
http://www.android.com/
2. Google play store.
https://play.google.com/store
3. Droid dream. Google android market kills droid dream malware in Trojans.
http://blogs.computerworld.com/17929
4. Intent.
http://developer.android.com/reference/android/content/Intent.html
5. Access permissions.
http://developer.android.com/intl/ja/reference/android/Manifest.permission.html