This can go in your .vimrc or in a global location such as /usr/share/vim/vimrc.
I would be interested in what other command line and vim users do to improve Snow Leopard.

step 1. Add following code to /usr/share/vim/vimrc

set nocompatible " Use Vim defaults
set bs=2 " backspacing over everything in insert mode
set ai " Auto indenting
set history=100 " keep 100 lines of history
set ruler " show the cursor position

set viminfo='20,\"200 " keep a .viminfo file

syntax on " syntax highlighting
set hlsearch " highlight the last searched term

filetype plugin on " use the file type plugins

" When editing a file, always jump to the last cursor position
autocmd BufReadPost *
\ if ! exists("g:leave_my_cursor_position_alone") |
\ if line("'\"") > 0 && line ("'\"") <= line("$") |
\ exe "normal g'\"" |
\ endif |
\ endif

step 2. Make alias vi = vim

open ~/.bash_profile and add following code

alias vi=vim

VIM: Making it Work on Leopard is a post from: My MacOS X