Ok, here we go. Its not the first time, some of Creative's FCC filing has been leaked. And some of these FCC filing did not go into production due to some reasons or another.
The Sound Blaster Wireless MultiPlay discovered by Engadget would attach directly to a PC and share its audio over 2.4GHz RF wireless to stereo speakers through receivers around the house. This is quite similiar to the Creative's Xdock
The system may be Windows-only as it would require a special Creative Media Server app to run. There may be a X-Fi component in this gadget which will up convert your mp3 music.
Besides, I think the ZiiSound D5 Wireless Speaker is already doing a good job and its a much better speaker system to have than the Sound Blaster Wireless MultiPlay.
Please feel free to let us know in the comments section below.