You can use this redsn0w from June to jailbreak 4.0.2 on iPhone3G and iPod2G(non-MC version). Just point it at the 4.0 IPSW (the public one, not the developer GM one). (Yes – point it at the 4.0 IPSW even though you’re at 4.0.2).
redsn0w 0.9.5b5-5
Posted inHOWTO
HOW TO: Jailbreak iOS 4.1 Beta 1
bout an hour ago, Apple released iOS 4.1 beta 1 to developers, and you can already jailbreak it using redsn0w 0.9.5b5-5.
Posted inHOWTO
Redsn0w 0.9.5b5-5 Released To Fix iOS 4 MMS Issues
The iPhone DevTeam just released another update to redsn0w which comes to version 0.9.5b5-5. Some users were unable to send and receive MMS messages, and if you are one of them, here is your fix.