The Broadcom chip actually has extra hardware for encoding and decoding a few other well-known formats. The Raspberry Pi foundation did not include these licenses because they wanted to keep the costs down to a minimum, but they have included the H.264 license. This allows you to watch HD media on your TV or use the webcam module.
They provide a way for users to buy separate licenses if you would like to use these extra encoders/decoders.
At the time of writing, the only project to use these hardware codecs was the OMX project maintained by XBMC. We will compile GStreamer-OMX later in the book, which can be used to stream a video from the Pi to another computer or watch HD video from the console.
You can go to http://www.raspberrypi.com/license-keys/ to buy licenses that can be used once per device. Follow the instructions on the website to get your license key.