I had the same thought - also note that the software powering the Squeezebox server AND the devices is open source! In fact they just flipped the player software (written in LUA) over to BSD, here's the commit:

http://svn.slimdevices.com/jive?view=revision&revision=8...

You can download nightly builds here: http://downloads.slimdevices.com/nightly/?ver=7.5

Backend is perl, and is GPL: http://en.wikipedia.org/wiki/Squeezebox_Server

The player software is written in LUA and runs well on OSX and OK on Linux (I am running the nightlies).

I have found the hardware players to be quite nice, and with iPeng on my iPhone I can control everything from anywhere: http://penguinlovesmusic.de/ipeng-the-iphone-skin-for-squeez...