According to Engadget, iPhone OS 4.0 may offer tethering on AT&T. Welcome as the ability to use an iPhone as a gateway to the internet will be, this is a mistake. Tethering is a terrible technology and introducing it at this late date is just stupid. There’s a much better way.
Palm had the right idea with the Pre (and apparently Google has the same idea for the Froyo version of Android.) Instead of tethering, turn the handset into a Wi-Fi hotspot, sort of a do-it-yourself MiFi. The advantages are considerable: Tethering is a miserable, fidgety, error-prone way to connect. Tethering a Windows laptop to a handset via Bluetooth is a black art and doing it over a USB cable is no picnic and a nuisance to boot (Macs work somewhat better.) With Wi-Fi, the iPhone would just behave like any other access point: find its SSID, enter a WPA password, and you’re in, no human sacrifice to the Bluetooth gods required.
Furthermore, any device that can connect over Wi-Fi, including an iPad, would be able to connect through the iPhone hot spot, whereas only devices equipped with the appropriate Bluetooth dial-up networking profile–the name alone shows its antiquity–can tether. That apparently would exclude the iPad.