How do I make terminal sessions resume on Lion with iterm2 and tcshrc
You could add something like this to the startup script of your default shell (mine is zsh, most people use bash, I guess, so you may have to tweak.)

Here's my bit of screen jiggery-pokery (in my .zshrc)

# Autoload screen if we aren't in it.  (Thanks Fjord!)
if [[ $STY = '' ]] then screen -xRR; fi


I got this from somewhere on the interwebs (I don't recall where, and I don't know who Fjord is, but good on him.

With this you can close your iTerm window, and it will resume where you left off when you reopen it.  I highly recommend reading the screen man page also.