Important update:
For those of you tempted by the SqueezeBox Duet AND who are already in possession of an iPhone or an iPod Touch, I have installed the iPeng app (10$, but worth it), which can be used with success instead of the SqueezeBox Controller (which is 75% of the cost of the Duet).
So, you can buy the just to receiver for 170US$. If I had known the iTouch was good enough (on some aspects even better), I would have saved myself a good 400CAN$.
Additional: if you install the iPend, make sure to power off then power on the iTouch or iPhone as the app is astonishingly slow at first. Once you reboot, it is very rapid and 10 times better than the lame "Remote" application made by Apple for iTunes.
