iOS version 5.1 update brings important features like a new camera application for the iPad and Siri for the Japanese. But not until 24 hours after Apple releases iOS 5.1, jailbreak tool is ready to use. iPhone Dev Team has been updated so that you can jailbreak redsn0w iOS 5.1 devices.
Keep in mind that this is a tethered jailbreak so you need to connect your iDevice to activate the computer any time. This tool works on all A4 devices: iPhone, iPad, iPod touch, not for A5 devices (iPhone 4S and iPad 2).
Click here for how to jailbreak using redsn0w 0.9.10b6 iOS 5.1.Software, Tips, ultrasn0w