RVM, Rbenv, ruby-build has already support Ruby 2.0.0. You can build it by them.

Install YAML lib

$ brew install libyaml
$ brew link libyaml

If you are using RVM:

$ rvm pkg install openssl
$ rvm install 2.0.0 --with-openssl-dir=$HOME/.rvm/usr
$ rvm use 2.0.0

Done.

Otherwise, you need install openssl manually:

Install OpenSSL

$ brew install openssl
$ brew link openssl

Install Readline(Optional)

$ brew install readline
$ brew link readline

If you are using Rbenv:

$ CONFIGURE_OPTS="--with-openssl-dir=`brew --prefix openssl` --with-readline-dir=`brew --prefix readline`" rbenv install 2.0.0-rc1

Here is the tranditional compile:

Although configure warnings configure: WARNING: unrecognized options: --with-openssl-dir, --with-readline-dir, but it truly works.

Otherwire, openssl will be broken when make, which will tell you.

$ wget http://ftp.ruby-lang.org/pub/ruby/2.0/ruby-2.0.0-rc1.tar.gz
$ tar xzf ruby-2.0.0-rc1.tar.gz
$ cd ruby-2.0.0-rc1
$ ./configure --with-openssl-dir=`brew --prefix openssl` --with-readline-dir=`brew --prefix readline`
$ make
$ make install

(Optional) Install Bundler

Install pre-version of bundler for Ruby 2.0

$ gem install bundler --pre