Playing OGG files
From Maemo Wiki
The Nokia Internet Tablets don't have ogg support out of the box, but you can listen audio in this format by installing third party software. There is a feature request to have Ogg support in the tablets out of the box, see Bug #176: Support for OGG Vorbis / Theora missing.
Gstreamer ogg codecs
These codecs run on the main CPU, not on the DSP.
Ogg capable players if gstreamer ogg codecs are installed
- UKMP
- Kilikali
- Exaile port for maemo
- Kagu (uses osso-media-server like the built-in player)
- YouAmp
Players with built-in ogg capability
- Mplayer
- Vorbis Player (for the 770 only)
- mpd
See also this (long) InternetTabletTalk thread: gstreamer with ogg vorbis support
There is information for developers to enable ogg support in their applications at the "Getting started with multimedia" how-to pages for maemo 4.x, maemo 3.x, and maemo 2.2)