iOS 4.1 has been jailbroken: "
I'm not an iOS user, so I'll keep this short and sweet: iOS 4.1, just hours after its public release, has been jailbroken by the notoriously nefarious Chronic Dev Team. The device used in the hack was an iPhone 4, but presumably any iOS 4.1 device will be exploitable in the same way.
It sounds like there's still some work to do -- you can't jailbreak your iOS 4.1 device just yet! -- but I expect it'll only be a matter of days before the exploit finds its way into the hands of the pearly white masses.