Edward Blake wrote on the Vorbis dev mailing list:
i've just ported libvorbis, libogg, and vorbisfile stuff to the pocket pc a while ago, it was pretty straight forward (just add a few more #ifdefs around the ftoi function and some others) and written a player for it.
It can be found at http://www.dot9.ca/~cyanphase/pocketogg/
(i havent seen anyone else doing this before so i hope i'm not repeating anything already).
i kind of stuck all 3 libs into 1 tho, i guess i was lazy, i'll fix that soon.
i'm not too satisfied with it just yet, i'm still trying to find out why the waveout code in the player doesnt work right with anything more than 2 waveheader blocks. (the Flags thing doesnt get WHDR_DONE set when theres more than 2 blocks, either a bug on my side or a bug in windows ce for pocket pc).
Edward Blake.