Ogg is an open standard for a free container format for digital multimedia, unrestricted by software patents and designed for efficient streaming and manipulation. Ogg is maintained by the Xiph.Org Foundation.
I’ve already written about: Why Linux doesn’t support mp3, allow watching DVDs and selected wifi cards out of the box? Short answer - copyright/IP laws prevent shipping all these software(s) and technologies/plugins with each Linux distribution. However ogg is free from patents issue.
Ogg support is installed by default on most GNU/Linux systems. This new site provides user friendly guide to installing Ogg support for both the Microsoft Windows and Mac OSX systems. Ogg support is installed by default on most GNU/Linux systems.
In an effort to rally support for the underdog media format, the Free Software Foundation has launched PlayOgg.org, a website promoting awareness of the Ogg format. It's an educational primer for playing Ogg Vorbis audio files and Ogg Theora video files on Mac and Windows desktops.
You can get more information at wired news : How To Live an Open-Source Musical Life With Ogg Vorbis (via digg)