How can I create a Postgres user and database whenever I create a new rails app?

I have followed this really helpful tutorial:

http://blog.willj.net/2011/05/31/setting-up-postgresql-for-ruby-on-rails-development-on-os-x/

I would really like to run rails new myapp and have the postgres db set up automatically. Is there any way I can do that using a Rails application template or something similar?