Not sure if it's bit rate peeling or just transcoding for new bitrates:

Vorbis Peeling

My first guess would be 'another one of these shareware transcoding tools', but who knows...

As far as I can see, it doesnt even claim to be a peeler?

Vorbis stream 1:
Total data length: 11035223 bytes
Playback length: 2m:53.266s
Average bitrate: 509.513952 kbps

Peeling the above file to:

Vorbis stream 1:
Total data length: 3312132 bytes
Playback length: 2m:53.266s
Average bitrate: 152.926449 kbps

.. takes less than a second on a 1.4GHz P4.

As the makers of 4Musics OGG Bitrate Changer don't say "instantaneous converting speed," I suppose they aren't peeling.