Tethering is using some type of mobile device to gain internet access on another device.
Tethering works by connecting a device that can access the internet (iPhone) to another device that cannot (i.e. your Notebook). This can be done using Bluetooth wireless technology or cables (such as USB), allowing the device without built-in access to connect to the internet, using the other device as a modem.
Starting from iPhone OS 3.0, tethering is supported by default. All you need is a configuration file for you Mobile Phone Provider like Swisscom, Orange, Sunrise, Vodaphone etc.. To get this file, check out the folliwing link.
it works like a charm! 😉