If you develop apps for the BlackBerry platform and submit them to App World, you'll know that the app needs to be reviewed this can happen. Within your BlackBerry vendor account there are guidelines to be found that gives you an outline for things your app should comply with but there was never any clear indication of why your apps could be denied.
Today that changes. RIM has released a BlackBerry App World Vetting Criteria document which lays out all the criteria needed to develop apps suitable for selling in App World. The five page document includes what kind of images are not acceptable, privacy guidelines, ads, functionalility and a whole host of other things.
So, before developing your app for BlackBerry App World, give the document a read to be sure it will get accepted.