This weekend at MyGreatFest, p0sixninja announced that they discovered five userland exploits for both the iPad 2 and iPhone 5. These exploits were discovered by the Chronic Dev Team and P0d2g who also discovered an exploit in the Apple A4 chip used in the iPhone 4, original iPad and iPod Touch 4G.
p0d2g and p0sixninja are members of the Chronic Dev Team, who were the key developers/hackers behind greenpois0n, which back then was the only method available to jailbreak iOS 4.2.1 completely untethered. Since this jailbreak will be userland-based, it will work on all iOS devices with an untethered jailbreak for iOS 5 at launch. Userland exploits can be patched by Apple in next firmware releases.
The iPhone 5 along with iOS 5 will be jailbreak-able immediately after it's launch next month, the Chronic Dev Team stated that they'd need to get their hands on a new iPhone 5 itself to see whether the exploits work.