Tether your iPhone with the Nexaria BC2 router

Go to system prefs -> sharing -> Internet sharing
-> then share your "iPhone USB" connection from drop down and the check the protocols to share the connection with: Ethernet, airport card (which creates wireless network), blue tooth, firwire.. -> hit start!

Or why tether?

Consider this - you get an important Word document. You open the email attachment, then use the iOS4 open to "open in..."

You open with say GoodReader, which caches a copy. You then send the file to your laptop using iTunes. You can then edit the file, synch it back to GoodReader, then email the file back out.

So I need tethering why...?

Or just get a MiFi.

I have a Sony Ericsson X10 Mini that runs Barnacle and serves perfectly well as a "mi-fi" for my iPod Touch and my netbook. Oh yes, it also takes calls. And I got it "free" with the data contract.

Or, if you can't bear to carry that other mobile OS, jailbreak your iPhone and set it up as your wifi hotspot. It's a $10 app, I believe.

OR... you can make any laptop with wi-fi connection a wi-fi hotspot. So if you have more than one device, you can connect them all to your laptop, which is connected directly to the iPhone.

The only use case I can see is if you want to share your iPhone's connection with an iPad or iPod... and you haven't got a laptop.
But if you've got an iPhone, you don't need an iPod touch. And you can get an iPad with 3G anyways...

I don't see the advantage here. According to the video, tethering has to be turned on in the iPhone. If that is the case, then why do I need this wifi modem?? Also, as soon as you turn on tethering with AT&T, you lose your grandfathered unlimited data plan and get the 2 gb per month option. Not good!!!