See http://object.io/site/2011/02/idiomatic-rspec-state/

concise_spec.rb

context "with a bit of state" do
  let!(:user) { User.create! }

  it "should be the latest user" do
    User.last.should == user
  end

  # .. more examples reusing the user
end

old_style.rb

context "with a bit of state" do
  before :each do
    @user = User.create!
  end

  # The following specs assume the user has already been created
  it "should be the latest user" do
    User.last.should == @user
  end

  # .. more examples reusing the @user
end

verbose_spec.rb

context "with a bit of state" do
  let(:user) { User.create! }

  before :each do
    user
  end

  # The following specs assume the user has already been created
  it "should be the latest user" do
    User.last.should == user
  end

  # .. more examples reusing the user
end