Mac OS X ships with a console version of Vim, but it is outdated and it was not compiled with Ruby or Python support. Command-T, for one, requires Vim to be compiled with Ruby support and thus will not work with the version of Vim shipped with the operating system. You may also have configuration settings in your .vimrc that are incompatible with Vim 7.2. Thankfully, there are a few rather simple options for updating Vim.

Simplest: Homebrew built MacVim

Homebrew is my favorite OS X package manager. If you’re not familiar with Homebrew, you should check it out. You can use Homebrew to install MacVim, which includes both a GUI and console version of Vim 7.3. Passing a simple flag to brew install will instruct homebrew to setup the necessary symlinks to replace the system console Vim with the version provided by MacVim.

$ brew install macvim --override-system-vim

# If you need the app bundle linked in /Applications...
$ brew linkapps

Note: Please see the caveat below concerning building Vim

Simple: Homebrew built Vim

If you don’t want the version of Vim shipped with MacVim, you can build Vim directly from source, also using Homebrew. Homebrew does not include a formula for Vim in its official repository as that would be counter to its (occasionally broken) [rule](https://github.com/mxcl/homebrew/wiki/Acceptable-Formula) to not provide system duplicates. There's a [formula](https://raw.github.com/Homebrew/homebrew-dupes/master/vim.rb) in the [homebrew-dupes](https://github.com/Homebrew/homebrew-dupes) repository that will get the job done in just a few short steps, however.

Update: The Homebrew maintainers have decided to break their rule against system duplicates in this case. The Vim formula can now be found in the main repository. The instructions below have been updated and this is now the simplest way to update console Vim, but I still like having MacVim as well.

# mercurial required - install if you don't already have it.
$ brew install mercurial

# install Vim
$ brew install vim

# if /usr/bin is before /usr/local/bin in your $PATH,
# hide the system Vim so the new version is found first
$ sudo mv /usr/bin/vim /usr/bin/vim72

# should return /usr/local/bin/vim
$ which vim

Note: Please see the caveat below concerning building Vim

Without Homebrew

If you’re interested in Vim, I’m guessing you’re also fully capable of using a package manager, but if you want to do this quickly and without involving Homebrew and without running afoul of the caveat below, you can download and install the MacVim app bundle and setup an alias to point to its version of Vim. Assuming you have MacVim installed to /Applications/, you can add the folowing to ~/.bash_profile or other appropriate configuration file.

$ alias vim="/Applications/MacVim.app/Contents/MacOS/Vim"

Caveat: Locally Built Vim

If you build Vim locally via Homebrew or any other method and you use RVM or rbenv to manage multiple rubies, you should be sure to switch to the system installed Ruby when building Vim and any compiled plugins (such as Command-T). If you build Vim against one Ruby and Command-T against another, the penalty will be a SegFault when launching Vim. In that case, rebuild both against a consistent Ruby.