Could not find generator rspec:install.

I'm trying to follow this tutorial here:
http://railstutorial.org/chapters/static-pages#top

When I run:

$ rails generate rspec:install

I get:

Could not find generator rspec:install.

What could be the problem?

Thanks.

Since I'm using Rails 3.0.0.0.rc, I got it solved by doing the
following:

$ gem install rspec-rails --pre

And, in Gemfile:

gem "rspec-rails", ">= 2.0.0.beta.17"

The steps were from: http://github.com/rspec/rspec-rails

Thank you.