Unlock iPhone Firmware 3.1

The team at iPhone Dev have released a Pwnage 3.1 Tool for use with the 3.1 firmware from Apple's iPhone.
This release starts with PwnageTool 3.1 for Mac OS X - which supports the iPhone 1st Generation (2G), the iPhone 3G and the iPod touch 1G. It DOES NOT support the 3GS or  2G/3G Ipod touch because of changes with Apple’s update techniques (that complicate the 3GS upgrade process).  They say, "redsn0w for Mac OS X and Windows will follow sometime in the near future, please don’t bug us about it - we’ll release when we have something ready"

They have some golden rules that you ought to follow. GOLDEN RULES

1. If you are using a 3G iPhone with ultrasn0w and rely on ultrasn0w to obtain cellular service, then you should only upgrade to 3.1 with a PwnageTool created .ipsw. - Stay away from Apple’s direct updates as described here and here please get up to speed on the whole subject by reading the information contained in these posts.
2. If you have an original iPhone (1st generation) then 3.1 unlock works with this PwnageTool release. iPhone 3G users upgrading to 3.1 will need to continue using ultrasn0w with a PwnageTool created 3.1 .ipsw
3. Please read all parts of this post before downloading and using these tools.
4. Read items 1, 2 and 3 again and again.
5. At the bottom of the post are the bittorrent files for the 3.1 capable version of PwnageTool.
6. This app is suitable for the recent 3.1 release.
7. This version of PwnageTool will NOT work for the iPhone 3GS.
8. PwnageTool WILL work for Original iPhone (1st Generation), Original iPod touch (1st Generation) and the iPhone 3G.

 After reading that, you can continue to learn how to tweak your device via their blog post here: http://blog.iphone-dev.org