How to Jailbreak iPhone OS 4.0 Beta using Redsn0w for iPhone 3G
IMPORTANT: This current redsn0w can only Jailbreak and not unlock/Activate OS 4.0. Apple has mandated registering with UDID to get past the activation process. If you are on an unofficial carrier and rely on unlock, DO NOT update to iPhone OS 4 Beta.
Step 1: Download iPhone OS 4 Beta and Update via iTunes (if not already) Duly check that the firmware file name matches “iPhone1,2_4.0_8A230m_Restore.ipsw”
Step 2: Download and Run redsn0w 0.9.5 (for Mac) and point it to the original iPhone OS 4 Beta firmware for iPhone 3G to proceed.
Step 3: Select “Install Cydia” and click “Next”. Make sure your device is both OFF and Plugged In to the computer before you click “Next”.
Step 4: Use DFU mode to install the jailbreak.
You will now notice that Cydia has a blank white icon. Also, Cydia has no sources. Go to the Sources pane and add http://apt.saurik.com/cydia-3.7 repo and restart.
How-to Enable Multitasking on iPhone 3G:
Enabling Mulitasking is not hard. Simply edit a N82AP.plist and change the “multitasking” key to = “TRUE”. If the is not there, add it on your own.
If you have any troubles, feel free to ask me @taranfx
iPhone 3g with Multitasking Enabled: