blackra1n RC3 is also live for both Windows and Mac!!! Clean firmware 3.1.2 and baseband 05.11.07 are recommended.

Updates:
Unlock!!!
Hacktivation
Keep legit activation if activated before running app
15 seconds faster, you’ll feel it
Tiger + PPC support

Go to blackra1n.com to download

It appears some users are having wifi issues. Try a “Reset Network Settings” Also, this just enables custom MobileConfig files. To fully enable tethering, go here on your iPhone and download a MobileConfig file for your carrier. Watch out for carrier fees for tethering.

Click here to view the embedded video.

[via geohot/boygeniusreport]

This release allows your baseband to remain unlocked at 3.1.2, but it does not unlock a new baseband put there by restoring to official 3.1.x. It is super important that people who need the unlock to understand they can keep it only by starting at 3.0 (or earlier) and updating solely to custom IPSWs that don’t update the baseband. For those who have been onboard the “unlock train”, simply install ultrasn0w via Cydia once you’ve restored to your custom IPSW. Don’t forget to turn off the “3G” setting in Settings->General->Network if you use T-Mobile in the U.S.A.

We realize we upset some folks (e.g. existing 3GS owners) with our earlier announcement that we wanted to hold onto the 3GS iBoot-family hole until 3.1 was out. Our aim there was to get as many people as possible onboard (within reason of course) before revealing the hole, since Apple will fix it immediately. But all of that became moot when the purplera1n release was made, since it uses the same hole.

ultrasn0w unlockers — You all must remain particularly vigilant against upgrading your basebands, since doing so will kill the unlock (for most phones, there’s no going backwards in baseband version). Apple has gotten very serious with the latest baseband — they’ve removed 180 (!) commands in an effort to cut down their exposure to holes. So please always stay away from stock Apple IPSWs and instead use our tools as we release them. These tools let you update your firmware without updating your baseband.

Those installing ultrasn0w will probably also need to do a single run of Settings->General->Reset->Reset Network Settings. We’re testing various fixes for that particular glitch.

redsn0w platforms — This is the first redsn0w release that also supports linux! It’s the newest version of the bunch, so any feedback would be appreciated. But right now, redsn0w should work on OS X, Windows, and linux.