This is something I'm curious about. Say you're using a BlackBerry and have BBM contacts on there, then you wipe the BB and sell it. Would the new owner still get all your messages or anything, because it's connected to the PIN of that phone?
shouldn't be a problem with the new bbm since it's associated with the email address. Just wipe the device, remove the associated email from BIS and bbm will be clean and clear.
With regards to the PINs - you are correct. The PIN is associated with the device and any PINs sent after sale will still go to the device.