I use PDANet so I’m unaffected by all this, but I saw this on TC’s mobile crunch and felt compelled to share. 🙂  Now again, as I remind my readers every time, there is a difference between jailbreaking and unlocking. {UPDATE:  the newest version RC3 now has unlock as well as jailbreak.  I have not tested it yet.} Although I am not unlocked, I’m keeping my phone as 3.0 until I hear otherwise.

Anyway, getting to the point…
Blackra1n is pretty dead simple to use. Go here http://blackra1n.com/ and download.

Plug in the phone, hit ‘make it rain’ and chill for 60 sec or so. Dont touch anything or you will screw it up. Once its down we go to step two.
The following is right from mobile crunches site, so I have not tried it..

# Look for the Blackra1n icon on your iPhone’s homescreen. Open the Blackra1n app
# Tap the label that reads “sn0w”, then hit the Install button in the upper right. This will unlock your phone for use on any SIM-compatible carrier, and reenable the IPCC hack required to enable tethering.. This part should take about 30 seconds.
# Once the unlock is complete, open Safari. Navigate to http://help.benm.at
# Scroll down the page and tap “Mobileconfigs”
# Find the proper IPCC file for your carrier. In the case of AT&T, that would be in U.S.A > AT&T. Tap this file, then hit the “Install” button. Confirm the resulting prompt, alerting you that the file has not been signed. Allow the IPCC file to install, which will take about 10 seconds.
# Close Safari. Hold the sleep and home button until your iPhone resets. This reboot may take a bit longer than normal.
# When your iPhone resets, go into Settings > General > Network > Internet Tethering. If you can successfully switch the “Internet Tethering” slider to “On”: Congratulations! Everything seems to have worked as expected.

Good luck kiddies!!