I could be wrong, but as far as I know, the SqueezeBox software isn't UPnP enabled, which is the protocol that NevoSL talks to media servers.
I played with some SqueezeBoxes a while back, didn't find a way for them to work with the NevoSL (besides IR of course) and just left that dream alone.
As far as the Duet goes, it's pretty much the same product as the SqueezeBox, but for about $100 more, the interface is on the remote, not the box itself. For both solutions, you still need something that has the media stored on it; like a PC. The remote looks pretty cool with an iPod-like wheel thingy, but as far as i know, it can't control your AV equiptment.
If you are looking to control media through your NevoSL, I'd try to source a Roku Soundbridge (any model). I used this device with my old NevoSLs and found that it could receive audio from the NevoMedia Manager software. Since I don't offer NevoSLs to my clients anymore (Nevo only produces the Q50 now), I do not know how good a Roku Soundbridge works with NevoMedia Manager anymore since Roku has released several new firmware updates for the SoundBridge during the past year.
I would image it works just as well though, but I don't know for sure.
Does anyone here use a Roku Soundbridge with current firmware and a NevoSL/NevoMedia Manager software combo? ....now that I think about it, I might have been using the TwonkyMedia software server...what a help I am, lol.