The Wall Street Journal today reports that Google is working on designing and marketing a home-entertainment device that would "stream music wirelessly through the home." The interesting part here is that Google might actually market this device. Chances are, after all, that the hardware will look pretty similar to what Google showed off at its I/O developer conference last year.
In the context of explaining its Android@home initiative (which, until now, hasn't really shown much promise), Google also showed a few Android-based music devices that featured wireless streaming and access to Google Music. Last year, Google called them Android@home hubs and the code name at the time was Project Tungsten. In the demo, Google used a tablet with prototype software that allowed its users to select different output devices – including the Android hub.
At the time, Google stressed that these were just "conceptual examples" and not actual products. It's quite possible that this is changing now and that Google is turning these prototypes into actual products.
Here is also a video to the presentation (the discussion of the music devices starts about 46:45 minutes into the video):