99cbe960_ackBerry_PlayBook_Tablet___2_1__Guideline
[Characteristic] Smaller screen size [Guideline] 
Stay focused on the user's immediate task. Display only the information that users need at any given moment. For example, a customer relationship management system can provide a massive amount of information, but users only require a small amount of that information at one time. Design the UI so that users can perform tasks easily and access information quickly.
Constraints of designing for mobile devices - Link - Find the latest UI Guidelines for the BlackBerry PlayBook Tablet - 2.1