The iPhone OS 4.0 was announced only yesterday (yay multi-tasking!), and already its been jailbroken by the always-crafty Dev Team. Of course, this doesn’t mean the official release will feature the same security flaws that allowed the exploit to happen. But I’m just guessing they’ll find a way to crack it, anyway…they always do.
The iPhone 4.0 OS is expected to be released this summer.