Agile Web Dev w/Rails - Password Change

Happy New Year everyone.
Just wondering if anyone has coded the ability to allow a user to change
their password following the way the book (second edition) implements
administration.

Sure.

Seems like I should be able to cut out the
password/password_confirmation portion of 'add_user' form to create a
'change_pass' form. The problem is I'm not sure how to go about having
it confirm the password and implementing the change. Seems the code will
only do that for new users.

You get new salt and rehash the password. I actually adjusted mine so
it re-salts every time the password gets updated.

  def password=( passwd )
    @password = passwd
    return if passwd.blank?
    self.passwd_salt = User.salt
    self.passwd_hash = User.hash_password( @password, self.passwd_salt )
  end

  private

  def self.salt
    Digest::SHA1.hexdigest( rand.to_s )
  end

  def self.hash_password( password, salt )
    Digest::SHA1.hexdigest( password + salt )
  end