iPhone Dev Team has just released a second beta version of Redsnow 0.9.5 tool that will help you to jailbreak iPhone OS 4.0 beta. The beta version of iPhone OS 4 was released and available for download earlier this month only for registered Apple developers.
The latest updated version, Redsnow 0.9.5 beta 2 brings some bug fixes and updates which includes, SMS and 3G data problems.
The official iPhone Dev Team website states that:
For those JB app devs who experienced SMS or 3G data failures, the new 0.9.5b2 download at the bottom of this page should clear things up. You’ll need to do a fresh restore to stock 4.0b1 before applying the new beta redsn0w update.
You can see the full step-by-step guide posted here about how to jailbreak the iPhone OS 4 using Redsnow 0.9.5 tool.
UPDATE 1: Redsnow 0.9.5 beta 4 has been released by iPhone Dev Team and is now available for download from here.
Download Redsnow 0.9.5 Beta 2