The iPhone Dev Team came through with their 2008 release date.  Although the software is still in beta.  There are a few features that are missing, but nothing real important.  They will continue to work on the software to make it perfect.

STEP 1:  Update to firmware 2.2 in iTunes if you have not done so already.  Make sure you have the 02.28.00 baseband by visiting Settings - General - About

STEP 2:  Launch QuickPwn and follow the onscreen directions to jailbreak/Activate your 2.2 iPhone 3G.

STEP 3:  Open up Cydia and download all of the important updates.

STEP 4:  Restart Cydia and click Manage at the bottom.

STEP 5:  Click on Sources.  Then hit Edit at the top left.  Click Add.  Then enter http://apt9.yellowsn0w.com and press Add source.  Once it says Return to Cydia, press that and then hit done at the top right.

STEP 6:  Click Search at the bottom and search for Yellowsn0w.  Click on yellowsn0w and install it.

STEP 7:  Press the home button after it has installed to return to your main screen.  Insert your new simcard.

STEP 8:  Open up Settings - General - Network and set Enable 3g and Data Roaming to OFF.

STEP 9:  Go Back to Settings - General - Reset and click Reset Network Settings.  Your Phone will reboot.

STEP 10: Once your phone has booted up, wait 10 seconds for a signal.  If you do not get a signal, eject and reinsert your sim and wait 10 more seconds.  You should have a signal then.  If you do not go to Settings and turn Airplane Mode on then off and you should have a signal.

-please note that if you reboot your phone and you do not have signal, flip the Airplane Mode on and off.