If you have a jailbroken iPhone or iPod Touch running software/firmware 1.1.2, you now have an automatic, graphical method for upgrading to a jailbroken 1.1.3 device without any host computer interaction. This is not "iJailbreak," (another computer-less jailbreak method) but rather a solution developed and sanctioned by the iPhone dev team. "iJailbreak" uses the same process as now-defunct "Nate True" hack, meaning it breaks "Nikita" -- Apple's method for signing appications -- and hence may prevent installation of official third-party applications when they are authorized by Apple. The new method, dubbed "Official 1.1.3 Upgrader," preserves Nikita, and is also less problem-prone in general than iJailbreak.
To use the new method: On your jailbroken iPhone/iPod Touch 1.1.2, simply launch Installer, then go to "All Packages," then select and install "Official 1.1.3 Upgrader." Make sure you are connected via WiFi and a charge source before beginning this procedure. All necessary files will be downloaded directly to the iPhone/iPod Touch and the jailbreak process automatically performed.
If you are using a different iPhone firmware revision or haven't yet jailbroken your 1.1.2 iPhone, see our complete 1.1.3 jailbreak guide and follow all of the steps except step #8, which can be done automatically with this new package.