This tethering is done through a jailbreak’ed app called MyWi.

Its an app you actually have to pay for which is weird given its a jailbreak’ed app but its well worth the 10 bucks and has a free 10 day trial i’m still using.
Its actually better then the old hack for tethering that you could do with a custom ipcc  profile, mainly because it still works but also:
- it can allow you to share your iphone’s internet via USB / bluetooth OR by turning your phone into a WEPd wi-fi hotspot multiple computers can join
- shows up and down bandwidth usage as it runs in the background with a nice graphical display
- doesn’t require a custom ipcc profile

This also seams to be the best route for this firmware version because:
- you don’t have to unlock your phone and it doesn’t involve a tether’d jailbreak (where you have to plug your phone into the computer whenever you restart)
You don’t have to install ultrasn0w, blacksn0w, blackra1n (or any other program with 1s or 0s in it)
- at 10 bucks it isn’t worth the time-sink figuring out another reliable way of doing this

Drawbacks:
- your phone will be jailbroken(?) and may be less dependable (and will have a pineapple for a boot up logo) though mine seams to be working pretty well so far.

Steps:
1. Connect your iPhone to iTunes and back that ish up.
2. Download PwnageTool_3.1.5.dmg from http://blog.iphone-dev.org/ and install it
3. Use PwnageTool to create a jailbroken version of the iphone firmware and load it onto your iphone via iTunes. I followed a step-by-step tute like this one
3b. Resync your phone with iTunes to get all your apps, music, photos, etc back on your iphone. You can do this later as it takes forever.
4. You should have your jailbroken phone up and running at this point with Cydia app on it. A very slow, crude looking, not-apple-app-store App Installer with way too many ads in it.
Open Cydia and click on the search icon in the bottom right and type “rockapp”, and install it (its another App Installer like Cydia but from another company, the same one that makes iWi).
5. Open it, click on MyWi, install the trial, load it up and you should be good to go

Good luck!
Mark