I was having a problem where my libiconv.2.dylib file in /usr/lib was corrupt and lots of applications were failing. I got a copy of a friends /usr/lib folder and was going to swap them out. Apparently I didn't think it through well enough because when I issued sudo mv /usr/lib /usr/lib.old all hell broke loose. Now Finder won't open, Terminal.app just keeps saying "Illegal Operation" and other stuff like Archive Utility doesn't work. I'm pretty sure that if I reboot my machine it won't start up at all.
How can I rename this back, or rename my friends copy to just /usr/lib (currenty /usr/lib.new)???