Yup! iPhone Dev Team has released Redsn0w 0.9.5b5-4 with a fix for iBooks app which was having some issues after jailbreaking iOS 4.0 on iPhone 3G and iPod Touch 2G with Redsn0w 0.9.5b5-3. Again this update comes for both Windows and Mac users. The procedure for jailbreaking iOS 4 on iPhone 3G and iPod Touch 2G with Redsn0w 0.9.5b5-4 is exactly similar to the first release of Redsn0w 0.9.5 here.
Remember: Jailbreaking your iPhone 3G with Redsn0w 0.9.5b5-4 will upgrade your baseband to 05.13.04 which still can be unlocked via Ultrasn0w 0.93. But we still recommend you to use PwnageTool 4.0 which can jailbreak iPhone 3G while preserving your baseband which could be helpful in saving you from the downgrade issues.
Update1: Download Redsn0w 0.9.5b5-5 to Fix APN / MMS IssuesContact Us for News Tips, Corrections and Feedback