Tony, there's already a stable build of Logitech Media Server for Raspberry Pi with playback. It's a fork of Squeezeplug: http://squeezeplug.de

Of course you could just install Squeezeslave on a RBP and have yourself a super-light and cheap SqueezeBox. With the caveat that it has no optical audio output and may not have the ideal analog output. You *should* be able to get digital audio out of the HDMI port however.