Here is a nice bit of information that I just picked up. The guys over at OSBB have just been able to obtain the airBrowser bar file that comes installed on the BlackBerry 10 Dev Alpha device, so you can install it on the PlayBook via sideloading. Credit goes to Sacha, one of the creators of the DingleBerry jailbreak for obtaining the sys file location to download.
Note: AirBrowser cannot easily be uninstalled. So make sure that before you install you are ok with it staying on your PlayBook.