The patent describes a system where the logo antenna would be mounted in an conductive cavity with a dielectric window covering the actual antenna structure. In this case, the window would be shaped like the Apple logo.
A logo antenna wouldn’t be as susceptible to signal interference from the MacBook’s all metal body, or the iPhone’s frame. It would also avoid signal loss issues some iPhone 4 owners experienced when holding their phone without a case on it.
The patent also applies to other electronic devices, such as watches and pendants, too. That could be a hint at future Apple product plans, but it could also simply be wording designed to block other companies from trying to steal the antenna placement idea.