Download Redsn0w 0.9.5b4 to Jailbreak iPhone OS 4.0 Beta 4

Redsn0w has just been updated to beta 4 to support the latest iPhone OS 4 Beta 4 firmware. iPhone OS 4 Beta 4 was released by Apple last week, which since Beta 2 has closed the jailbreak loophole used by Redsn0w 0.9.5b1 and b2 to jailbreak OS 4. But with this latest version of redsn0w, you should be able to jailbreak iPhone OS 4 again on iPhone 3G.

An excerpt from iPhone Dev-Team on this release is as follows.

This is a beta release of redsn0w targeted at developers of jailbroken apps. It uses the same pwnage2 DFU-mode exploit that we’ve been using since the 2.x days. Nothing new is revealed to Apple, and it’s not applicable to the iPad. Don’t go near it if you use yellowsn0w, ultrasn0w, or blacksn0w.
YOU SHOULD STAY CLEAR OF THIS BETA SOFTWARE IF YOU RELY ON A CARRIER UNLOCK. That’s because the beta redsn0w works only if your device has already been upgraded to the stock 4.0beta1/beta4 IPSW from Apple, which contains a baseband update. If you installed that IPSW, you’ve already lost the carrier unlock until the next planned release of ultrasn0w and blacksn0w.

Instructions to jailbreak iPhone 3G on iPhone OS 4 Beta 4 using Redsn0w 0.9.5b4 are exactly similar to the last release. Please read all the instructions posted here carefully before upgrading your phone to iPhone OS 4 Beta.
Download Redsn0w 0.9.5b4 for Mac
Download iPhone OS 4.0 Beta 4