New post: Ruby Memoization

Here I would use a more real example like:

> The simpler way to use memoization in ruby is by using the conditional assignment operator: ```||=```.

```
class User
   # other methods
  def facebook_friends
    @facebook_friends ||= FacebookApi.get(:friends_list, self.facebook_id)
  end
end
```

> And when using `facebook_friends` you don't do uneeded calls to facebook api, because the result is memoized:

```
user.facebook_friends # => query the facebook api and return the friends
user.facebook_friends # => return the memoized friends
```