Android applications do need to be converted from Android format (APK) to PlayBook/BB10 format (BAR) then loaded from App World or "side loade" with the developer tools.
The functionality is built in but you won't see any evidence of that from normal use until you start an Android application. You may not even know before hand that the app came from Android if the App World blurb doesn't tell you.
Have a look at this
CrackBerry post.