I'd like to know something similar. If linuxMCE supports UPnP (either as a server or client). This is how the Xbox360 works with WindowsMCE Connect. Right now I have a UPnP share from a windows pc and would like to share/stream it to my Ubuntu box. I know GeeXBox can do this, but its interface currently leaves alot to be desired.
UPNP support is not added yet, but you can use gmediaserver application from ubuntu to stream audio files on the network using UPNP. you can type for example this code in a startup script that can run on your hybrid:
apt-get install gmediaserver
audio_dirs=""
for dir in /home/user_*/data/audio /home/user_*/data/other /home/public/data/audio /home/public/data/other ;do
[[ ! -d $dir ]] && continue
audio_dirs=($audio_dirs "$dir")
done
echo "# Serving audion files from : ${audio_dirs[@]}"
killall gmediaserver 2>/dev/null
gmediaserver --friendly-name="LinuxMCE" -b ${audio_dirs[@]}