So many are confused about how exactly to jailbreak to 1.1.2
If you are running a 1.1.2 phone you need to get back to 1.1.1. This method is documented countless times on this site and the rest of the web. If is also included in the readme file packaged in the zip file linked below.
Now that you have a 1.1.1 phone you need to get installer working.
Install OktoPrep via Installer
upgrade to 1.1.2
Conceited software has released software that will jailbreak 1.1.2, installs installer, and install ssh app. Both windows and mac versions are available and you can get them here:
Run the conceited software 1.1.2 jailbreak software, it will take about 10 minutes to complete.
Note: if you did not install OktoPrep before you upgraded to 1.1.2 none of this will work