I have tethering working between my laptop and my IPhone without using a jailbreak. The speed is great and it was very issue to do. I had to double check to make sure that my wireless router connection was turned off. This is very cool. The process can be found at

http://www.ismashphone.com/2009/06/a...one-os-30.html

Everyday the list of reasons I switched to an IPhone gets longer :)