You may have noticed that Homebrew doesn't include VIM in it's repositories. This is because they don't support "duplicates" which means that any command line tool that comes pre-installed with OS X will not be in their repository.
There is a workaround though and it involves using homebrew-alt.
Unfortunately the vim formula in homebrew-alt doesn't work if you happen to have Ruby 1.9.2 installed, so for now you'll have to use my fork.
# Install VIM brew install https://raw.github.com/AndrewVos/homebrew-alt/master/duplicates/vim.rb # Rename old vim to 'vim72' so that we can still access it if we need to mv /usr/bin/vim /usr/bin/vim72
Now if you restart your terminal and check the VIM version you should see something like this:
$ vim --version VIM - Vi IMproved 7.3 (2010 Aug 15, compiled Jul 23 2011 20:09:39) MacOS X (unix) version
Great! You now have a more stable VIM.