A fast, integerized implementation of the OGG Vorbis decoder, capable of running faster than real time on processors such as the Cirrus Logic 7212/7312 is available from http://sourceforge.net/projects/ivdev/

The Cirrus Logic 7212/7312 is a 74Mhz ARM processor (likely the same or something similar to what is used in the rio receiver).

Would be neat to see such decoding support added to the recent arrival of client software (e.g., Dave's excellent RioPlay).