Playing OGG files
The Nokia Internet Tablets don't have ogg support out of the box due to lace of development of kernal drivers for the built-in DSP, but you can listen audio in this format by installing third party software, which uses the CPU. 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.
There has been some work by community members enabled by the release of the DSP toolchain on the the Texas Instruments TMS320C55x DSP being released to the public, but essential propreitary components are still licensed and under NDA by TI in the form of the Code Composer Studio IDE.
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
- Canola2, requires this extra install to enable the scanning of .ogg files (more info here).
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)