OGG Vorbis audio files can be included into HTML page using the <audio> tag. However the browser need to support HTML 5 to play it.

OGG Vorbis files can be played by a flash player. However FlowPlayer and some other players do not support OGG, although the Adobe Flash Player 10 allows to play OGG Vorbis files (labs.adobe.com/wiki/index.php/Alchemy:Libraries)

Although I like open royalty free formats, I must admit that currently OGG Vorbis support is very limited.