After weeks of that mind-bogglingly obscure viral web campaign, Sony has finally revealed the full details about its new Rolly "Sound Entertainment Player" device in Tokyo.

It seems the little egg-shaped gadget is an MP3 player (although with only 1GB of memory) as well as a Bluetooth wireless stereo speaker, with some pretty gimmicky features.

The big news is that the device is motion controlled - it contains sensors that know which way is up, so that volume can be adjusted by turning the player clockwise or anti-clockwise, tracks can be changed by rolling the player forwards or backwards or shaking it.

As has been predicted, like the Muiro speaker, the device will "dance" to your tunes. "Packaged" moves will be available to download but software will also be released that will let folk make up their own Rolly moves on their computer.

The display-less Rolly will play MP3 files, as well as ATRAC, streamed via Bluetooth from your computer (and we assume, mobile phone).

New video shows the "dancing" to take the form of spinning on the spot, turning, flapping its end cap bits and flashing blue and green lights.

The 300 gram Rolly is due to go on sale in Japan at the end of September and will cost 40,000 yen - which converts to around £175. It offers 5 hours of battery life.

No word on an international launch as yet, although you could speculate this "cute" effort has all the hallmarks of a Japan-only product.