Is it possible to render different actions based on what fails at validation?

For example - I have one field in the form - email addres. It is validated like this:

validates :email,
          :presence   => true,
          :uniqueness => { :case_sensitive => false }

In the controller:

def create
  @user = User.new(params[:user])
  if @user.save
    redirect_to somewhere
  else
    # render :new if email is blank
    # redirect_to somwhere if email is taken
  end
end