[aiharkness]

BlackBerry branded apps on BBOS devices will require a BlackBerry data plan. Some third-party apps, those that use BlackBerry services, will also require a BlackBerry data plan so as to be able to access the services.

See what others say about finding out which is which. I think if it were me I would ask the developer ahead of time before paying for an app. In the case of free apps I would just download and try.