The Dev Team has jailbroken iOS 5 just 3 days after Apple released it to developers following WWDC.
Update: Windows version now available
Props to the Dev-Team once again for releasing a jailbreak very quickly for the new beta. Keep in mind this is a tethered jailbreak with redsn0w, meaning you will need to connect your device via USB to have it boot jailbroken. Once this is done you can disconnect and remain jailbroken until you reboot the device.
Full details available at the Dev-Team Blog: