yep confirmed by the iphone dev team iPhone 3GS can be jailbroken and beacuse of that unlocked with Ultrasn0w

1. Ensure you have upgraded to iPhone OS 3.0
2. Jailbreak your iPhone 3G using redsn0w or PwnageTool (this will also install Cydia/Icy)
3. Run Cydia or Icy
4. Please add the repo repo666.ultrasn0w.com to Cydia or icy
5. Search for ‘ultrasn0w’ in cydia or icy and install ultrasn0w
6. Reboot your iPhone 3G
7. T-Mobile USA users should disable 3G before using ultrasn0w
8. Enjoy
Thx to The iPhone Dev Team

Mac

* http://bentkowski.com.pl/redsn0w-mac_0.7.2.zip
* http://foskarulla.com/redsn0w-mac_0.7.2.zip
* http://download.desteini.com/mac/redsn0w-mac_0.7.2.zip
* http://theiphoneproject.org/mac/redsn0w-mac_0.7.2.zip
* http://begolli.com/downloads/mac/redsn0w-mac_0.7.2.zip
* http://www.highphone.org/redsn0w-mac_0.7.2.zip
* http://iwannahack.com/extra/Evilbenking/redsn0w/redsn0w-mac_0.7.2.zip
* http://iphone.awayfrombrain.ch/pwnage/redsn0w-mac_0.7.2.zip
* http://www.ipodtouchmasterfr.com/files/redsn0w-mac_0.7.2.zip
* http://StealthyHosting.com/download/redsn0w-mac_0.7.2.zip
* http://ivwriting.com/redsn0w-mac_0.7.2.zip
* http://asifzia.com/redsn0w-mac_0.7.2.zip

Windows

* http://theiphoneproject.org/windows/redsn0w-win_0.7.2.zip
* http://begolli.com/downloads/win/redsn0w-win_0.7.2.zip
* http://www.highphone.org/redsn0w-win_0.7.2.zip
* http://iwannahack.com/extra/Evilbenking/redsn0w/redsn0w-win_0.7.2.zip
* http://iphone.awayfrombrain.ch/pwnage/redsn0w-win_0.7.2.zip
* http://www.ipodtouchmasterfr.com/files/redsn0w-win_0.7.2.zip
* http://StealthyHosting.com/download/redsn0w-win_0.7.2.zip
* http://ivwriting.com/redsn0w-win_0.7.2.zip
* http://asifzia.com/redsn0w-win_0.7.2.zip

* http://www.revotech.org/mirror/PwnageTool_3.0.dmg
* http://www.istation.at/pwnagetool_3.0.dmg
* http://neon.hexxeh.net/PwnageTool_3.0.dmg
* http://www.itouchmaster101.com/PwnageTool_3.0.dmg
* http://www.zackoch.com/iphone/PwnageTool_3.0.dmg
* http://just.legalizecanna.biz/PwnageTool_3.0.dmg
* http://www.neonkoala.co.uk/files/PwnageTool_3.0.dmg
* http://g.appleguru.org/PwnageTool_3.0.dmg
* http://o.schwarzmetall.cn/PwnageTool_3.0.dmg
* http://www.macdotnub.co.cc/downloads/PwnageTool_3.0.dmg
* http://theiphoneproject.org/mac/PwnageTool_3.0.dmg
* http://begolli.com/downloads/mac/PwnageTool_3.0.dmg
* http://d01.megashares.com/dl/b9276a6/PwnageTool_3.0.dmg
* http://downloads2.touch-mania.com/jaillock/PwnageTool_3.0.dmg
* http://ivwriting.com/PwnageTool_3.0.dmg

Yep thats true folk firmware is released:

iPhone 1st Gen
Download iPhone1,1_3.0_7A341_Restore.ipsw

iPhone 3G
Download iPhone1,2_3.0_7A341_Restore.ipsw

iPhone 3Gs:
Download iPhone2,1_3.0_7A341_Restore.ipsw

this is a  quote from the the bigboss website

Yes, 3.0 GM is released to developers. This is the final 3.0 release. There is no jailbreak for it at this time. Do not yet upgrade. There are rumors of people using the 3.0 b5 jailbreak tools. This is a terrible idea. It will replace most your 3.0GM with B5 components. You will not have a real 3.0 final any longer, instead you will have a hybrid 3.0 and beta 5. It’s a terrible idea. Next week when beta 5 expires, your 3.0 jailbreak could expire as well and you would have to restore all over again.Yes, some people may claim that they did this and “it works fine”. But as I just stated, it is not a real 3.0 final any longer. Definitely not a good idea nor is this something you want. Just wait a few days and you should be ok

Speed
• Faster than the previous generation: Launching messages is 2.1 faster, load the NY Times in Safari: 2.9 times faster.

Camera
• New camera, with auto focus, auto exposure, and auto white balance.
• You can also tap to focus, changing white balance in the process. That is neat.

• Special macro and low light modes.

• It supports video, 30 frames per second VGA with auto focus, auto white balance, and auto exposure.
• Can trim video with a tap of the finger, and share it with MMS, email, MobileMe and YouTube.

Connectivity
• It supports the 7.2 Mbps HSDPA standard.

Graphics
• Includes hardware to support the OpenGL|ES standard, for faster and more complicated 3D games.

Design

• Same design as before.
• Greener materials: Arsenic-free glass, BDF-free, Mercury-free LCD.

Special features
• It has a compass application, which works with the included magnetometer. It’s integrated into the new maps, showing orientation, alongside longitude and latitude.
• Voice control. You can now talk with your iPhone, Enterprise-style. You can instruct it to play similar songs to the one you are playing, or call people.
• Nike + support built in.
• Supports accessibility features, like zooming on text, inverting video, and voice over when you touch whatever text is on screen.

Battery life
• Increased battery life.

Price and availability
• $199 for 16GB version.
• $299 for 32GB version.
• Available on June 19th.

Thx to Gizmodo