for tethering, there are 3 kinds right now,
first, USB tethering, which means cable tethering, but needs driver from the connecting side to support it
second, Bluetooth tethering. It uses bluetooth to connect to ur device, and ur device will use ur phone as a bluetooth modem to connect to the internet
third, Wifi tethering. It use the built in wifi to let ur phone act as a router-alike device, allowing more then one device to connect and share ur 3G connection.
for now, TF supports 2 and 3, so there's no need of cable. However i would suggest using bluetooth tethering, cos it uses a lot less battery compared to Wifi tethering, and u don have to worry that someone might tap into ur connection. Also, Wifi tethering have 2 type as i know, Hotspot and Ad-Hoc. Hotspot will show ur Wifi as if it's from a router, like iOS 4.3 tethering, while Ad-Hoc would be like connection to another peer device. The latter is not supported in TF unless u apply some fix which require rooting.
anything that other find wrong or misleading feel free to correct me, this is based on my own understanding on tethering
