How does the internet tethering works on the PB??

Does anyone have an idea how the PB Internet Tethering works?

uses bluetooth and your phone acts as a modem, it uses your current data plan from your phone if your carrier and plan allow it

Did you search the Playbook forum itself as this one is for Apps & Games.
You should find plenty of information there.

Also remember that bridge is not the same as tethering.

Tim