Yes, BoyGenius jumped the gun a little bit by saying that AT&T-Apple was endorsing USB modem tethering of the iPhone - they aren't and won't.
That doesn't mean you have to give up the dream, however. Bluetooth DUN Modem tethering has been available on the iPhone since July of last year - it was acually one of Nate True's first hacks. Check the video for more
Also, for step by step instructions (from September) on using WiFi (tiny proxy) as a modem on the iPhone, check here.
If you haven't jailbroken your iPhone, what are you