Still no iPhone tethering
When the iPhone OS 3.0 was first announced one of the features that got many iPhone owners excited was the ability to tether the device to a notebook. AT&T threw water on those flames of excitement when it announced that it would not allow tethering of the iPhone.

With that week’s announcement that AT&T would allow VoIP apps to run on its 3G network many hoped that would additionally be followed by tethering. For now AT&T is still saying no tethering is going to be allowed for the iPhone.
AT&T says that it won’t release a feature until it is certain the user experience is good. I think most of us would agree whether AT&T wants to follow that mantra, the user experience we have now isn’t good. 30% dropped calls is not normal.
[Source] Shane McGlaun