some days ago I recieved something very interesting. Something many of us have hoped for. A new audio decoder for the PMA!
A friendly guy named Matthias Welwarsky has written an plugin enabling the pma to play ogg/vorbis files using the Tremor library.
The sources(GPL) for the plugin can be found here:
You can get the ipk file here:
To ogg-enable your PMA you'll just have to install the ipkg and restart qtopia. The plugin won't be enabled before you restart either qtopia or the whole operating system.
 http://www.vorbis.com/ and http://xiph.org/vorbis/