Yes, however at this point you need to downgrade to 1.1.1, jailbreak it, install Installer.app, use it to install OctoPrep, upgrade to 1.1.2 and then use iphuc to put Installer.app back onto the iphone.
So, if you really want to, you can and there are guides posted on TUAW that will teach you to do it. However, as I see it it is much more important for me to be able to use my phone as a phone than to risk something screwy happening through downgrading and then re-upgrading.