[mxcl]

It's worth pointing out that "sudo is up to you". So leave /usr/local alone if you like. Or install Homebrew to ~/homebrew. Whatever you choose. Homebrew was designed to be flexible and non-intrusive.

However the suggested step is suggested because:

1. On OS X /usr/local isn't even there on a fresh install, so nothing that should run as root is there by default.

2. Mostly people use Homebrew to install a few tools that are missing, these tools don't need to run as root, so they are as vulnerable as TextMate is (because you dragged it from the DMG to /Applications and it installed as your user).

Now you can argue that you should thus install to ~. And you can of course. However I've found over the last eight months that a great deal of build systems have bugs and don't find dependencies if you install the deps outside of /usr or /usr/local. So for a trouble free life we suggest /usr/local.

Finally sudo is dangerous. You should only use it with tools you trust. Do you really trust a half baked Makefile made by a developer who doesn't really know how to write Makefiles?

All in all I think depriviledging /usr/local is safe and the least hassle for Homebrew on OS X.