Remember the BlackBerry PlayBook root method that was discovered last week. RIM announced that it would be investigating the exploit and releasing a patch to close the hole. Well, it seems like RIM has kept to its word and true enough - the hole which dingleberry uses to gain root access has been closed by the latest update that has been issued to the PlayBook. It looks like the short-lived root method will have to find another way now to gain super user permissions on the QNX tablet.
However, it's been reported that you can always downgrade to an older version of the PlayBook OS to root it, or just not update the tablet to keep root.
Ubergizmo, BlackBerry PlayBook update disables dingleberry root
