[UPDATE] It seems both of these games were made free to PlayBook users compliments of RIM. The titles have been updated to reflect this in App World. No specific reason as to why RIM did this but hey, we're grateful!
Gameloft has made two of its most popular games, Asphalt 6 Adrenaline HD and Modern Combat 2, available to PlayBook users for free. I personally love A6A. It's a great racing game that's a little more easy to use than Need for Speed which is what's made me like it the most. Make sure you get these games right now because we're not sure how long they will be free for everyone.