Apple released the beta version of the next firmware iOS 4.2 . This new firmware is available for download to developers at the moment , and final release will available in November. Apart few bug fixes , there is no added feature than wireless printing in the new iOS 4.2.
We suggest , you stay away from this release if you want to jailbreak or unlock your device . Keep an eye on the GreenPoison Updates . Latest Twitter updates suggest , shatter exploit based bootrom jailbreak will be released next month [ Oct ] before the official iOS 4.2 release [ Nov ] , so that means we will be able to jailbreak iOS 4.1 [current stable version] on iPhone 4 . No further upgrade advised .
Also stay away from downloading iTunes 10.1 beta release until further notice from the dev team .
Stay tuned for coming Jailbreak Updates .