I have been waiting for OverDrive to bring their OverDrive Media Console to the BlackBerry PlayBook. From what I can tell they have done it by using the new Android Player to port their Android app to PlayBook OS 2.0 so this is OS 2.0+ for now. In case you are not familiar with OverDrive they provide you access to over 18,000 libraries worldwide to get both eBooks and AudioBooks. You can check them out from Libraries nearby or even load your own ePub eBooks though I have not managed to get that to work yet.
OverDrive Media Console is definitely one of those apps that you want to have installed on your PlayBook if you have OS 2.0. You can pick up OverDrive Media Console free in App World.
Thanks Ron for sending this in via Nerdberry!