Technical note: "Ogg" is only a container; the audio codec is "Vorbis".
Pro: Ogg Vorbis is efficient (clearly surpassing MP3) and patent-free. Using MPEG4 AAC instead (which is about equal in efficiency) might cost license fees.
Con: The Ogg container is not the most efficient and flexible; as long as it only contains Vorbis audio, it is fine, but in case of mixed A/V content, other containers (like Matroska) are to be preferred.
(And the Xiph staff might sometimes not be as flexible as necessary regarding relations with the industry.)
_
Somehow I cannot load the hardwarebug.org site, but our satellite connection is unreliable... or "slashdotting the site" killed it like a DDoS attack, see Wikipedia // P.S.: Long live Google cache.