Marantz offers in Japan a 3 speaker surround sound system dubbed Marantz Opsodis Theater ES-150. As you can see in this customer photos you need quite some space under your TV to place the system.

Nikkei.Net (Subscription) reports that Marantz (D&M Holdings) is planning to release a single 3D sound box that integrates all three boxes of the ES-150 so to speak this fall.
The size of the Marantz Opsodis Theater 3D box will be around 40 inch in length.
Opsodis stands for optimal source distribution technology which is aimed to provide realistic sound including clear high-pitched tones.
The new Marantz 3D box might compete with the Yamaha YSP-1/1000/800 sound projectors. I actually just ordered a Yamaha YSP-1000. So stay tuned for a review of it coming soon.
The Marantz Opsodis Theatre ES-150 was launched at the end of 2005 for about 350,000 yen (~$2,980).
More details on about the ES-150 on the Marantz site (Japanese).