If you wanted an idea of what the Native SDK on the PlayBook would start allowing in terms of ported resources then here is a good example. Some of the BlackBerry faithful have been having fun porting DOSBox onto the BlackBerry PlayBook. DOSBox is an emulation of DOS that has been popular over the years. It opens the door for some nostalgic MS-DOS programs to run especially after you shoehorn it onto the PlayBook using the regular sideloading method. BBin got a video and some basic instructions here.
If you want to take things a bit further Shane has some relatively simple instructions on how you cant take this further to get Windows 95 (Without internet) running on the BlackBerry PlayBook. Check out the instructions here though you will need a Bluetooth keyboard to get most of this working.
Let us know how your tinkering goes!